Reviews – Share your experiences

This is an amazing piece of art. Build it together with my wife and have a lot of fun making our own songs. Although very basic songs it is amazing that this machine can play it. love it and highly recommend building this!

THis is awesome. GOt one of each type left or right. used it my own ball machines and some in the ones from pvproductions

This was a joy to build and took several days. It did take a while to get all parts moving smoothly which promptly stopped when I put balls on it. However I did get it going and managed to record a short video of a complete circuit. Next step is to find out how to combine it into a larger loop. Great job PVP.

Just what I needed. Have several nxts and a few ev3 laying around but with the latest sets there are the new lego powered up motors included. I needed a way to make them work together. This cable solved it for me. thanks!!

As with the GBC 45, I built the GBC 41 on my own, in a week or two. The track worked well straight away, but because we don't have that many balls we had to fill the tipping box with stones. My husband did that job. Then there's driving the bulldozer, which is more something for my son-in-law. A question that requires a lot of practice. Our grandson also adds a ball in his own way :). Teamwork! See video: https://www.youtube.com/watch?v=eTmaRCjw7Ww Net als bij de GBC 45 heb ik de GBC 41 alleen gebouwd, in een week of twee. De baan werkte meteen goed maar omdat we niet zoveel balletjes hebben moesten we de kiepbak vullen met steentjes. Dat klusje heeft mijn man geklaard. Dan nog het besturen van de bulldozer, dat is meer iets voor mijn schoonzoon. Een questie van veel oefenen. Onze kleinzoon voegt op zijn manier ook een balletje toe :). Teamwork! Zie video: https://www.youtube.com/watch?v=eTmaRCjw7Ww

What a fantastic ball track you have created with GBC 53/54. Very fun to build and works perfectly, my compliments and on to the next one. Bart. Wat een fantastische ballenbaan hebben jullie gemaakt met GBC 53/54. Heel leuk om te bouwen en werkt perfect, mijn complimenten en op naar de volgende. Bart.

I built the track myself, my husband helped with the fine-tuning. For example, ensuring that the balls actually end up in the loading container. Programming was a thing, I had an outdated version of the instructions. Well helped by Marion, updated the building instructions and software, then got everything working. So much fun! Now going to try GBC 41 :) https://www.youtube.com/watch?v=eTmaRCjw7Ww

wow this is so cool! love music and lego technic. this combines best of both worlds. will also use this machine with my students (we have a lego technic program at school). a big plus for the included songs to play around with! recommend this one to anyone!

wow this looks pretty in the dark! got 2 of them controlling with the powered up system. I can make my own light pattterns. Used it in my lego ferris wheel and a GBC. Recommend!

I've been building a pirate ship and it came with different size axles. the manual shows the axles but I'm not sure what size they are. I've been looking today for a ruler that would help me out with the axles. And for some reason came across your site and it showed the technic ruler with the axle and the numbers on the side of the ruler. I said wow that is what I'm looking for. So this is why I'm buying this product. I would like to thank you guys for having this available. It will help me out a lot.

Very nice build. Sometimes difficult to get the pneumatics working but with the help of the finetuning guide in the beginning of the building instructions I was able to make it work.

Got the 42131 D11 for Christmas from my lovely wife. Thank you. But already knew about this great ball machine that i could build from the same parts. Awesome. So last week i dismantled the bulldozer and started on this. And wow, I have to say this is so impressive, you have to build it yourself to fully appreciate it. All the little details and clever building techniques. I have build quite some lego technic sets but this is for sure from another level. and never seen before mechanisms which absolutely blow my mind. How can one come up with such a machine. For example the wave machine. and the elevator. I was familiar with the lego powered up app but decided to try pybricks now as this machine supports it. Great that you dont need to use your phone for the machine to work. if you have the d11, then build this as well, you will be amazed!

I am sending this because my son wanted to show his Geneva Drive. He built. played, disassembled and rebuilt Geneva Drive for some times since August. Children played GBC #49 Geneva Drive and #52 Flight Fair this holiday. Those GBCs made our holiday much more fun. Thank you for all those products and services, and we wish you all a Happy New Year. https://www.youtube.com/watch?v=jNWcArWUUGs

I am sending a picture of a letter my son wrote to you. It says: —- To: PV Productions I like your GBCs! I am also happy that Flight Fair is finally finished! Thank you! —- See here the GBC 52 Flight Fair: https://www.youtube.com/watch?v=5qwoo7QJJfE Those GBCs made our holiday much more fun. Thank you for all those products and services, and we wish you all a Happy New Year.

Bought 2. Work well but be aware the plug that goes into the Technic hub can be inserted upside down and won't work. Strange that the plug this end doesn't have the notches on to prevent this. Make sure the contact pins of the pv plug face down when the lego hub is upright!

GBC 52 is a new twist on moving the balls. The catapult mechanism is a new and simple one. I loved the incorporation of the propellers to "propel the balls" so all can yet again line up for being deployed. All in all a solid build, some fine tooling required. Motor speed needs to be experimented with. Because of the lunching mechanism design, used a stronger engine. Simple . low cost and efficient. See also my video here: https://www.youtube.com/watch?v=is51lucMWIw

This is a very flexible light strip which fits very good in my lego builds. can wire it trough the lego holes and gaps and makes my builds pop. Great in dark but during the day it also has a nice effect. For some models the light line is too long. In that case I roll them up and hide it inside. Can recommend this one!

The tow bridge is very clever and I like it a lot. Building the machine was easy and I learned many interesting building techniques. The mechanism which switched the rotation of the drive axle is cool to see in action. I recommend this great ball contraption for you of for your kid.

I believe it is one of the best builds yet, with very stable lift mechanism simple conveyer belt and great use of gravitational forces for the „tilt-drop“ . The wave mechanism needs some tune-up but works well after. Dismantle and build about 8 -10 hours , Worked in the evening. I actually dismantled my CAT11 to build this. YouTube Video https://www.youtube.com/watch?v=YeBVlC0f5K4

Finally able to connect my new train motor (with powered up connector) to my beloved lego power functions system. great stuff and i will get more soon

I bought this instructions for my son's 7th birthday gift, as he requested.  He is not a big fan of LEGO but really likes GBC videos. He made a few small GBC modules by watching examples from GBC promo videos before, but it was the first time for him to build a GBC module by following building instructions.  With some short breaks, my son took about 8 hours to build the module himself. For him, this was neither too difficult nor too easy, neither too large nor small, but there were a few exciting challenges and lots of fun to build and play.  The instructions were clear and detailed. Timing mechanisms, geneva mechanism, and arms of the caroucel might be more challenging, but they were actually not, because of the detailed "Fine Tuning" section.  On the other hand, the geneva mechanism snagged every round because a large bevel gear connected to a weapon barrel  (#6 on Page 18)  and a small bevel gear under the ratchet mechanism (#13 on Page 24) didn't mesh properly. To solve it, axles/axle-pegs connecting a weapon barrel and shell 3x1x2 technic beams needed to be adjusted by a little poking and prodding, about 0.5 mm or so (Page 19). It was tricky because what he needed to adjust was not the bevel gears themselves but other parts. When my son solved it, he was really excited, looks super happy and proud.  The LEGO Technic 42120 set is a retired product in our country, but I was fortunately able to purchase the 42120 set. Like other PV-Production's instructions, it was really awesome that all the parts came from a single existing LEGO set and we did not have to gather parts up from here and there.  Only if the instruction was printable. It seems that books/prints are still easier for this age group of children to follow instructions. It feels like more than just STEAM learning. It was a big hit and still is. My son wants more PV-Productions' building instructions, and I'd definitely buy.

Im impressed by this gbc. especially like the 3 arms which feed the balls to the other arms. recommend it if you have this set!

hell yeah these rock! Got them as a gift from my beloved wife and now running multiple of them in one big layout. Also looking for the looping part you guys have but that is for my next birthday ;)

Nice build! My son (6) loves GBC videos on youtube and this was a perfect way for him to get started. It helps that all the parts come from an existing lego technic set. It means that from 1 technic set he can build 2 models from the original instructions, and then this one and then the other pv productions model that uses 42121. He needed some help for certain steps (and sometimes we had to go back and figure out where he went wrong), but could do a lot himself and he felt really proud of himself when he could see it working with the motor and funnel! Thank you.

This has to be one of my favorites perhaps. me and my kids really enjoy the tow lift and the operation f it!!

I needed to know about this cable much sooner! I got the inverted splitter cable and copy cable and used it in my train with 3 lego powered up motors! Now I can make longer trains with more power and still use the powered up hub.

Glad I discovered pv productions. exactly what I needed for my ongoing project and i can finally use my power functions motors again in the new lego system. Thank yyou!

Building the model was a lot of fun, for sure! Programming was very easy. To see the mechanisms working is fun as well. There were some issues. Parts come loose, especially around the shooter mechanism. Balls got stuck. I enforced some parts, and replaced others (like using normal axles instead of the "self-made axles" on pages 25 and 158). After some tweaking, everything works as expected. This has to be my favorite GBC I build so far.

Very convenient

Had to get this soo much sooner!! Now I can finally add my other lights to models without adding yet another power source, hence if your model already used Power Functions or Powered Up motors or lights. The big win for me is also that it saves soo much space so I can make my models smaller. Need to get another one soon

Very clever model. I could never think of anything like this. well done.

This is such a fun little GBC with and very impressive mechanism. Definitely build this one!

YES! After building the gbc 15 and gbc 21 I was very pleased to see that pv made another gbc out of the bucket wheel excavator. One word: amazing. The instructions are clear and the machine works well. However I had to make a few tweaks but that is normal with any gbcs as these are more complex machines. For this gbc it helps to make sure there is enough clearance between all the moving parts. Then everything works smoothly. looking forward to your next gbc!

Why did I not fin d this adapter earlier, would save me so much frustrating. Finally can I use my nxt motors with the new system from lego. why does lego not make this themselves...

This was fun to build and the design is very clever but ultimately I wouldn't recommend it for beginner builders. It simply isn't reliable enough, things like gears falling off because they're not properly secured shouldn't be acceptable to the designer. Instead of adding yet another module and running out of parts, proper reinforcement should be done first.

I initially didn't pay much attention to this set due to me not owning the 42100. But then I saw the tremendous play potential of the Dozer, and seeing that I do own the required pieces, I purchased the instructions and built the set in red and yellow colour. The set worked very well mechanically, and almost never jams, which is great considering this is my first PV GBC and a 3,000+ pieces build effort. My target audience was a toddler. He loved to play with it so much, often being totally engrossed in it. This set is much larger than other GBCs due to the fencing. Due to its size it's not easy to reinforce it so it often breaks apart and requires reassembling. It's also not easy to carry it around due to its size and sparse reinforcement. There are pros and cons to building GBCs with existing sets. They are very accessible in terms of sourcing parts, and that's what got me into GBC building. It also has downsides, like the compromises that had to be made, weird building techniques due to the lack of optimal parts, wrong color, etc. Overall I am very happy with the design and hope to build another PV GBC model soon.

A beautiful piece of art I would say. Amazing how it's build. Some important notes: some rotating parts are not turning completely free, so there is some fine tuning to be done while building. At one place I even used a metal spacer to keep the turning parts from getting "stuck". Otherwise....a must for lego builders.

Great build , needs adjustments but all in all a nice outcome . Video can be found at. https://youtu.be/QbcRgxVnrIQ

Fast shipping, excellent quality, large quantity, cheap price compared to most. Brilliant!

Overall a fun build. It loses some balls here and there and sometimes they get stuck. I had to rebuild some parts where the friction was not enough to get axles to turn.

Ordered yesterday after 3pm CET, arrived today before 1pm. Fast delivery and grabbing the right stick for my gbc module went much faster

After making several GBCs, now I made the GBC30, in one word 'fantastic'. Good manual and after a few small tweak and tuning everything. On to the next GBC 36. Na het maken van meerdere gratis GBC's nu de GBC30 gemaakt, in 1 woord "fantasties'. Goede handleiding en na enkele kleine aanpassingen werkte alles. Op naar de GBC 36.

Works great as a replacement for the LEGO Vestas set, where I replaced the standard motor with a Build-HAT/raspberry-pi controllable motor.

got my gbc looping yesterday in the mailbox. clicks just in place and works well. It is important that the table surface is level as otherwise there is sometimes a chance that a ball rolls to the side. Great fun!

Motor as to be expected. used it in the gbc 43 so it runs with me having to rotate the handle. Works great in combination with the usb power box from pvproductions. I used the 9V and the PF version. both options work good.

I can watch my gbc balls go round and round forever haha and I love how they just click into each other. I first used them in the GBC 45 as intended but quickly also started to design my own gbcs using the looping. It is smart to have a backup plan in case a ball cannot make the full loop. I started with a similar design like gbc 46 and 45 which works for me.

I was amazed when I saw the video of this. I instantly wanted to build this. It's pretty straight forward to build, as long as you're not in the final phase where you need to adjust the rope and the rubber band. I tried quite a few things to get it run smoothly, but didn't got it to run more than some minutes until the rope would stop, the cars would leave the track or the rubber bands would stretch too much. It is very tricky to set up. Even some own ropes did not do the job very long. It's still a very remarkable build - I like the track with the rectangular corners very much and how the cars drive through. But be aware that the adjustment takes quite some time and maybe several atempts. I needed to run it for 1 hour, which was by far not possible. A very beautiful build! With tricky setup! If you take the challenge with enough patience you will have a lot of reward!

I was very impressed by all the clever mechanisms in this build. I guess it takes an incredible amount of time to get all work smoothly together with only existing pieces. I still have trouble to get the automatic elevator module to work reliably. I will tweak it with some own pieces, because I will need to have it run an hour or two reliably. I wonder if this will be possible. You will need A LOT of balls for this to run as intended! The motor power for this is quite at the limit too, even if one pays attention to friction. It works - but don't load it with anything more ;) It would be helpful, that the highlighted pieces in the instructions would better be another color - one that is not used in the set. All in all a highly recommended build! It's a fun build! Great to look at.

A very nice and fun build!! The instructions were clear and very well made.

Rubber bands are oke. Not much else I can say about them.

I'm truly reliving my olden days (70s, 80s) when playing vinyl was still a common thing. A few years ago I started again with playing vinyl as it becomes more and more popular again. Now building my own turntable with LEGO absolutely blew my mind. It is nice to understand how these machines work and how the sound is being produced and influenced. Thank you for the good work.

This is absolutely awesome without purchasing another set of LEGO! I have been looking for the products encouraging my son to try GBC for the first time. There are fascinating videos of GBC, but no LEGO product is related as a starter. My son is 11 y old with massive knowledge and experience with LEGO. He started losing interest when he turned 10. Now, thanks to this product and instructions sets, he is back in business. I’m glad he found it intriguing so that he doesn’t get bored when he is required to stay at home during the pandemic. I will definitely continue to find the similar product once he completes two versions of instructions!

Love this build. Had so much fun with it.

Impressive, has not lost 1 ball.

amazing module. 6/5 if it could.

Bought two of the "PU Technic Hub" variety and am very happy with them so far. I am currently using them to power some Lego Control+ models with a 20Ah power bank instead of AA rechargables. The product is more sturdy than it looks from the images and fits the housing neatly. Shipping to Germany was quick and hassle-free. If a similar box for Lego Boost becomes available, I am ready to buy it.

Very useful tool to have around in my lego room

Top service !! Gisteren besteld vandaag in de brievenbus ... Deze site is een ontdekking 👍🏻 Top service !! I ordered yesterday, received it today in my mailbox (NL) ... This website is a true discovery 👍🏻

Bought a few for a case where my Powered Up motors needed to be far apart and they work great, will certainly buy a few more soon.

A large GBC, rather complex in its form and its operation (I would have put it in "medium" by the way), and take advantage of many particular parts (not Technic). Lots of movements allow the balls to move up and down in several places. It's a pleasure to see those movements follow one another with good timing. For these reasons, it is a model worth building. I stayed with the manual movement because sometimes the balls are blocked or come out of the rails, despite the care taken in the balancing, so I can adjust the shot by moving slowly.

The adapter cable works perfectly. Installed it in a motorized parcel train with two engines. The wagon is very easy to steer. You can find more information on my YouTube channel STEINeZEIT: https://www.youtube.com/watch?v=Ajwp5X65qZI (minute 5:32) Das Adapterkabel funktionier perfekt. Habe es in einen motorisierten Packwagen mit zwei Motoren eingebaut. Der Waggon lässt sich sehr gut steuern. Mehr Infos gibt es auf meinen YouTube Kanal STEINeZEIT: https://www.youtube.com/watch?v=Ajwp5X65qZI (minute 5:32)

Great first build of a GBC module. Worked like a charm in the beginning, but after a while it started to jam caused by the mechanism that toggles a ball left or right. I rebuild that particular part, and it went well. Apparently the mechanism to swing the arm demands some force.

The AA battery replacement kit works as intended and is a good solution to never have to change batteries again in any static MOCs. I would have liked to get a sheet with instructions on how to install them, since only one way is correct and I'd have to check the images on the product page to see which way. It would also be nice if there was an option to purchase a compatible charger brick with the set. Otherwise, all good!

It works great with static MOCs or to spare batteries while testing and debugging code... just be careful not to use 4 large angular motors (part 45602) with it because it will drain too much current - I know because I did it :D The large angular motors draw way more current than all the other LEGO motors.

The cable was installed here and works perfectly. Check the video on my Youtube Channel STEINeZEIT at minute 5:32 https://youtu.be/-DtgSvraZlg?t=332 Das Kabel wurde hier verbaut und funktioniert einwandfrei. YouTube Kanal STEINeZEIT https://youtu.be/-DtgSvraZlg?t=332 ab 5:32 zu sehen.

Nice little car which I think looks really cute. After this car I build the GBC 41 where this car belongs in. So much fun pushing the balls forward and being part of the gbc machine. Also very clear instructions and you should definitely try the gbc 41 Power pit Mania after you finished this.

Great GBC! It is my second from PV, and was a great success. The only problem I had was that I could not get the bridge to work properly. But seeing as lots of other people got it right this is probably just me. I will replace it with the flex conveyor and the big funnel, witch I have built a good stand for. The Elevator took a bit of trial and error, but got there in the end. Thanks for adding to my loop!

A good GPC for which I like the "jerk" movement, via the clicking system. Good idea for using Gear Racks and the belt drive system. Assembly was quick and easy, without even having to adjust anything ! I appreciate the possibility to add a motor, and to plug the output ramp towards to another module.

I really liked this set. Instructions were clear. The mechanism that toggles a ball left or right (not motorized part) sometimes jams at my build. Could be me misplacing a few bricks though as I am not a very experienced builder. All in all I picked up a few new building techniques and had a lot of fun building hours extra with this. So definitely worth the money, at least for me.

Easy to build but a bit harder to get working properly. My blue gear wasn't gripping and slipping quite right but I had a spare that solved the issue. Great entertainment for all three generations in our home once it was running.

This works a treat as you tend to run the motors for much longer on a GBC than on a vehicle. Great

Mechanism works well, PDF instructions are ok. I bought these for my five year old son who does not yet know how to read. The password protection on the PDF can be challenging since when he accidentally closed the instructions on his Ipad he needed me or my husband to retype the email to get back in. The watermarks on the instructions cover the parts diagrams and assembly info on a couple pages. That all said, the mechanism works well and my son had a great time putting it together.

Generally excellent. Some of the build images are off-centre and obscured by the PV-P watermark in the top-right corner. Some of the build steps are also small requiring zooming in and out repeatedly to be able to complete the build. Sometimes you have to skip a few steps forwards to work out where a part or sub-assembly is fitted as it's location can't always be determined in the diagrams.

My boy loved this kit, he still plays with it more than a month later. This GBC version of the kit is more satisfying than the original plans.

After some finetuning got it working as it is supposed to. Great look!

They work well in the 42100 GBC. Only downside is that they are a bit bouncey which makes them end up on the floor sometimes.

I am an AFOL part of OhioLUG. Together with other members we put on shows throughout Ohio and show off our large creations with Lego – usually city themed but we’re working on expanding that! My works range all over the place from mechs, to city, to hangable wall art, and of course GBCs! This is not my first GBC from you guys and will not be my last! Fun fact: I purchased the set on good faith that you’d release a GBC for it and was very excited to see the release of these instructions! Thank you for all of your work!

It was much, very much fun to build marble circus. And it ran well. It lost few marbles at the output of the Zigzag and funnel, because directly after one another a set of 7 marbles come directly, followed by 7 marbles come to the point to be taken up to the 'step-up module'. In order to not to bother about battery changing I purchased a Power Functions powered adapter. With the adapter the GBC system runs much faster. I tried three phone adapters. One normal adapter gave hickups (not enough power), but the charging adapter of my iPad and the Quick charge adapter of my Samsung phone makes the GBC run.

I guess I’m not the only dad who re-discovered Lego at the time his kids were old enough to build. These days, Lego Technic is much more elaborate and intricate than it used to be. So, it’s big fun for big kids as well. As my 4 year old is a huge fan of all things involving marbles, we thought it would be nice to tear the cement wagon to pieces and give this a go. This is the first GBC I built and i estimate it took me about 4 hrs to complete (I neatly sorted the pieces before starting). The instructions are quite straight forward, with some minor challenges with the perspective. I found the model a bit more complicated, or at least less fool proof, than your average Lego model, so it did involve a bit more trial and error. However, it’s also that more rewarding in the end when you have a fully functioning GBC. Looking forward to build some other models as well!

Liked the build, overall clear instructions. Only the final page does not show where the conveyors should go (although it is obvious). Getting it to work is a bit more tricky. Some of the challenges I came across: - balls got stuck on the white table (fixed by increasing the angle) - wide conveyer got stuck on the carrier beam (connect with a shorter connector: part#6013938) - balls dropping of the high conveyor (added a small side fence to catch the wayward balls) - gears dropping off on bucket wheel and at the rotating ball lift (torque makes the gears move sideways) - balls get stuck in the buffer of the ball lift (modified by making the opening smaller; only one ball fits at the same time: this helps to stack also in the slide towards the buffer rather than bridging off at the transit poit) Every run is still fun though.

This GBC is as cool as it looks. I could watch it for hours. Instructions were great. Some tweeking is necessary as is explained in the instructions, but that is part of the fun. I also ordered the orange GBC balls and the USB powerbox PF/PF connector. They balls are great. The USB powerbox works like a charm and is a must have if you do not want to be looking for batteries ever again. Also, the customer service is amazing! Will definitely shop here again!

My son and i liked the build. Very clear instructions. Nice job.

Great experience. Easy to build, but not boring. Must have...

Parts of this set are great, other a bit less (however understandable using only parts of the 42100 set)! The shovel dump action is super fun and makes your heart beat faster, but the dozer doesn't have enough friction in the wheels so we had to put a piece of paper down so it could drive the balls up the hill. I also wish there was some way to make this set run unattended. I think the lack of moving functions can be improved if you rethink the dump/dozer. There are still motors to use, so I'm looking forward to another version that uses 42100. Thanks for the build though!

This is the perfect GBC for me in my layout when I'm on conventions. Great length and flexibilty with the track layout. Like the fact that you can even lower and rotate the seconds belt

A well built and solid GBC. The movements are pleasant to watch, especially the climb of the stairs by the balls which is even fantastic ! Once again, when looking at the bricks used to build the model, especially the staircase, and their number in sufficient quantity, we would think that the original set was made for this GBC ! The gameplay of the pinball machine allows some interaction, which is not always possible with a GBC. The possibility to add a Lego motor is also an undeniable advantage to be able to play it. Excellent work !

This is my first ever GBC build, and I like it. It was pretty easy to build and I ordered GBC glowballs with it. I have been building legos for 4 years and I like this GBC better than the hovercraft. Matthew age 8

Despite being fairly new to Pv-Productions, and a fair bit of mistakes from time to time on my side, I'd say that this GBC has been an absolute blast to make and this is definitely a hobby that i would like to expand on. Big thanks to the Pv-Productions community and their help center

A compact GBC which intelligently takes up the theme of the pneumatic from the original model. We can appreciate how pneumatic is integrated to self-regulate : a piston used to change the direction of the other piston, ingenious ! Most of the parts have been used, the whole set is pleasant to look at, and the slowness of the pneumatic system allows you to fully appreciate movements. Very good work !

An enjoyable and fun build. Recommended

A fun build with the grand-kids. they loved dropping the balls on the keys.

A nice, good instructions build. Recommended

A GBC quite large, considering the number of parts. I like the possibility to add an engine which is better to appreciate the show. And I note that it's possible to adapt it for using with other GBC, a good idea. The funnel is also a crazy thing, I love watching the balls spiraling, especially when you put a lot of them !

Great engineering using available parts from 42009. Instructions are about 300 pages but could be shorter if some left/right parts are combined. You better build this part on a removable base or on a table. The structure is not rigid enough for you to bring around when fully assembled. You may need to adjust some gears on the automatic door and ball dropper few times before the mechanism works as intended. By far the most difficult part of this build is the whole "rope and rubberband knot". If you tie the knot too much it will derail when the knot goes through the "tan" colored gears. Meanwhile if the knot isn't secure enough, the rope will get pulled out after several laps eventually. Don't even get me started on the rubberband knot. Suggestion: Unused 2pcs Lego String with end studs may be used to secure both the ascending track and descending track so they do not have gaps. Common household heatshrink-tube wrap can be used and formed to conceal the remaining rope. This is important as you have to leave some length of rope behind the cart to prevent it getting caught in some places.

This was my first ever GBC build, and it was hugely enjoyable. It was amazing to see the stepper module come together - it's mesmerising to watch! The interactive elements made the GBC's operation even more interesting with pieces left to make some obstacles of your own. There is a fair bit of flex in the structure but this is easily reduced with a few basic liftarms/beams from your own collection. The ingenuity of this alternative build is so impressive, you would honestly think Lego had picked the pieces specifically to make this GBC. I found the challenge and enjoyment of the build considerably more satisfying than the donor hovercraft model. Thanks!

My first GBC. Well, it's really impressive to see how an helicopter could transformed into a stuff with balls. And all works fine ! Before starting, I wondered how balls could stay right on wings, but indeed they are well catched ! I just needed to adjust one gear so that timing of wings is correct, and another one onto ball delivery. That's all. Good job !

Nice balls. Good color.

Hello, as I've been buidling up several different MOCs with the #42082 I had time in quarantine now and just finished building up the GBC 36 - funny build but to make it run the whole time you really need a lot of balls to do that... any possibility to improve that cause I only have around 70-80 balls from your side on hand.. The inlet of the tower sometimes gets stuck - is it possible to improve it? What's the difference between v1 and v2 - as I've seen there's a new version available for download and it has 495 compared to 494 sides.. Thanks for your help, keep on building and stay healthy Thomas

Very interesting building, details can be only understanding buildling it. Very fun.

Thanks for the amazing model, great instructions

Wonderful modell. My son spent a very nice time building it. The instructions good be exported with a better resolution and without a white frame all around. In that way it would be much more comfortable (larger) to view on a pad as the instructions are not printable.

It's a really good thing to play with, you can design many templates and they are beautiful

This was our first GBC module too, my son (age 11) and I (mom) were so excited to be able to build something so cool! The instructions are absolutely fantastic, so thorough and easy to read step-by-step. The attention to detail is remarkable, every piece and function is accounted for and works exactly as shown in the video. We will definitely be purchasing more instructions from PV-Productions! Just have to buy more Lego first.. and make more space in our playroom :)

Great work! I built it without the optional Funnel XL. The instructions are very good. I really wonder how you do this. It's one thing to plan and design a GBC element without limitations on the parts. But creating a closed loop with interesting elements by using almost all parts of a defined, limited set of parts, is amazing. Im really looking forward to try out of the Bucket Wheel Excavator GBCs.

This was my first time building a GBC. It was awesome! Can't believe someone came with up this. When it was done I had to tweak some things to make it run smoothly, but no big problems. Love it, keep up the great work!

It was a lot of fun building this machine. Thank you for the instructions. I installed the GBC Funnel XL and made some changes to install the GBC Funnel Turo Spin. The GBC runs very well and no longer loses balls after fine adjustments. You need about 225 balls so that all parts of the GBC run without traffic jams.

Great GBC. Building Instructions very good.

It works great, good UV intensity but if you want to turn it on/off independent of the motors you cannot use LEGO Power Functions switch. So an independent LEGO battery or a USB Power Bank might be necessary.

Nice glow in the dark balls, practically identical to LEGO original balls with a spooky effect. Also react to UV light so work very well with the UV LED strip.

Thanks for the instructions. they where great

What an awesome way to have more fun and value from this set! It worked perfectly and were just excited and happy to look through the mAny posibilites and imagination people come up with. Also the customer service of this company is beyond any company we’ve seen before. Very quick, friend and super efficient. Highly highly highly recommended!

The UV LED strip either works with the Power Functions battery box or is connected to a micro USB. I would recommend the latter and use a simple power bank as it is easier to charge again. Two tips: The closer the gbc glow balls roll to the UV LED strip and the longer they stay in the vicinity, the brighter they shine. Take notice: The strip has a rubber-like surface, so that the balls tend to get caught if the assembly is too tight. The strips can be super easily installed due to the nice dimensions and with a few Lego Technic parts without having to be glued on: all you need is a black 3-axis spin, a 2-axis and two thin 1x2 lifting arms, one on the bottom and one on the 2-axis and the axis turns. The UV LED strip can be clamped in the space between the two axes and the lifting arms and then inserted into the lifting arms at any point thanks to the pin.

hey, guyz! thanks for the instructions! gonna test with my two children today. one thing bothers me - what is that last "tray" used for? a separate part looking like an upside-down table with 6 legs???))))

This was my first GBC that I made and seemed like a great entry point (can never argue with FREE instructions). It was a medium challenge technic build that took a couple of hours to build. For a full review, check out my website which also has a Youtube review: https://www.mattelder.com/lego-videos/what-is-a-lego-gbc-great-ball-contraption-review-time-lapse-fire-rescue-first-responder-to-gbc-34

I have built this with my son. We had great fun! Fantastic and clear instructions. We tweaked a few points to make it run more smoothly. Thank you for this!

Model after building is ok - as per description. For me manual is not HD - when opened on 14 inch laptop steps are very, very small. I do not understand why you did place approx. 7 steps per page - there should be second manual option with one step per page. When you zoom the manual pixels are visible so it is not HD version. Also some steps are hidden by watermarking of PV production logotype. Manual also has a lot of space for my details that manual is for me - it could be used for better quality of manual and also watermarks could has my data from the very beginning. So only 3 start as manual - 1 star, set - 4 stars.

Works very well - very good addition to my Lego!

Excellent instructions and the model is brilliant!

I like size of this GBC. I am really surprised, model works flawless. I think it works too slow to use it in layout. I like idea with rotatable ramp. Nice for small home layout. Final rate: 7/10

The models are OK. For some reason the page layout of the PDF's is not OK on MacOS. The content runs off the page on the right side, so you can't read parts of the text. When I use Adobe Reader on MacOS everything seems OK as it should be.

The instructions are excellent, of a high quality and resolution, and were easy to follow along. Great value for money, and a painless ordering and paying experience. The build was easy enough (instructions are actually even better than TLG ones in my view). I was very happy with the finished module, and the design of the ratchet mechanism is very clever (so simple, but effective). I did battle a little bit to get the module aligned nicely, the driving arm that connects to the ratchet mechanism kept snagging, but with a little poking and prodding of axles it was sorted. My advice would be to ensure that you have the ratchet mechanism working smoothly and without any friction or snagging of the parts before you put the conveyor on. The module runs well and with some fine adjustments to part alignment the drive mechanism settles down. It all works well and is consistent and reliable in mini loop mode. I bought this module with the intention of modding it for large GBC displays for our LUG. To get to one ball per second I added a lot more friction pins to the conveyor built to pickup balls more regularly. I simplified the drive mechanism, and moved the electric motor and a new gearbox to closer to the drive shaft of the conveyor. The input basket was increased in size to prevent ball leakage, and I modded the output ramp to allow for left/right side dropping of the ball into the next module input. If you are just getting started, none of these changes are necessary Overall, as someone with a bit of experience in GBC, and with a fair knowledge of Technic building (both sets and some MOCs) I think this is an excellent set of instructions. The module is an excellent introduction to anyone who hasn't built a GBC Module before, and as PV state on their product pages, the instructions and building of the module really do get you thinking like a GBC creator. It is also an excellent eye-opener for how far you can take a relatively small amount of pieces to create a complicated machine. I look forward to getting another set of instructions soon!

THANK YOU!!! It has been my second GBC Instruktion for 4255, and it is even better than the first one I got. I really love to build them. GREAT!!! Ulrike

My 7,5 year old daughter built it. With exception of pages 67 & 68 she built it compltely by herself. Pages 67 - 69 should be re-done as it is impossible to assemble the way it is suggested. Other than that this is a great build which is enjoyed a lot by the whole family.