GBC 25 Sweeper – 42049 Building Instructions

Rated 5.00 out of 5 based on 1 customer rating
(2 customer reviews)


Note: This Great Ball Contraption (GBC) is entirely made out of LEGO parts from an Official LEGO set.

Detailed building instructions of the GBC 25 Sweeper.
Made from parts of LEGO Mine Loader set 42049.

– Full HD PDF building instructions
– Brief with tips & tricks
– Extra pictures
– And more

Difficulty level: Easy – Medium – Hard


This GBC is in collaboration with Matt Norman.


Example Building Instructions

Note: This Great Ball Contraption (GBC) is entirely made out of LEGO parts from an Official LEGO set.


It has never been easier to build a complete Great Ball Contraption (GBC) loop yourself! GBC 25 features a mesmerizing module which covers a full loop so the ball flow never ends. Using a more accessible LEGO Set and focusing on one single mechanism this GBC is by far the best GBC to get started.

This GBC is entirely built using only parts from the LEGO Mine Loader and can be referred to as model C of the 42049. This GBC makes sure you master the GBC building techniques and tricks so that you eventually also can build your own GBCs. By default the whole machine is powered by hand but it can easily be upgraded with any LEGO motor (more information in the building instructions).

This GBC works great with our GBC balls.

Did you already check out the rest of our 42049 C Model family.



Master Timing & become a true engineer!


Learn about the wonderful world of mechanisms by building our GBC 25 Sweeper which features a highly efficient, perfectly synchronized ball Push Module. Based on agricultural machinery we have created this GBC Sweeper. Because the whole GBC is on wheels you can hook it up to you LEGO tractor or truck and drive it around.

Balls have to be inserted in the bottom input of the module. The module then picks the balls one by one and guiding them to the next stage. 4 perfectly synchronized push arms work flawlessly together to accomplish getting a GBC ball to the top in one fluent movement. The balls will be pushed out of the rail and return to the base via the return path. By doing so the loop will never end.
This GBC has an extra feature which allows you to easily remove the return path and put your GBC 25 in a bigger loop and combine with other GBC Modules.

Because this LEGO 42049 set doesn’t include a LEGO motor by default, this GBC loop is hand powered by rotating a handy handle. However we created pre-designed motor mounts so you can easily upgrade this GBC loop with any of the LEGO Power Functions Motors available and make it go on it’s own. How cool is that! Batteries can easily be replaced.


Don’t own the LEGO 42049 Mine Loader? No worries! This GBC is build using a lot of ordinary LEGO parts which makes it really easy to build this GBC without even owning the LEGO 42049 Set. When watching the video and checking upon the building instructions you can easily see which parts can be replaced (e.g. using a different color etc.). See also the part list in the product gallery below. Which cool color scheme can you come up with?

Fun Fact: Designing a GBC from such small part inventory really took all the ingenuity and experience we gathered over the years. Parts are being used in a new way and many problems had to be solved for getting this GBC to work and making it sturdy and reliable. Using over 97% of the parts that come with the set we really did get the best and most out of the original LEGO 42049 set. There was a real challenge to build a GBC from such a small set but we succeeded again.




Get the GBC Balls and accessories

The GBC Balls are available HERE.
Also take a look at our accessories.




GBC 25 Sweeper all over the world

Did you also build one of our GBCs yourself, with your friends or family? We would love to see and share it! Send us a picture or video via one of our social media channels or get in touch via email.



Change log latest update

v1 23-02-2018: Launch

v2 07-03-2018: Added additional information for the ball return path, motor upgrade and different use modes. See page 6 till 8.

v3 24-06-2018: Update building instructions to new standard. Fix step order issue. See page 31.


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2 reviews for GBC 25 Sweeper – 42049 Building Instructions

  1. Violet111

    got the 20 gbc module too. very different but i like both

  2. Rated 5 out of 5


    Bought this as my first one to try out. Works great! See the full review on Eurobricks (

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