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LEGO Great Ball Contraptions: starting small

A LEGO Great Ball Contraption (GBC for short) is a machine that passes LEGO soccer balls or basketballs through a series of complex modules – sort of like a Rube Goldberg machine. They require a good deal of planning and engineering skills, and are an interesting challenge for LEGO fans who would like to experiment with something more complex. ๐Ÿ™‚

There are many excellent examples of Great Ball Contraptions on YouTube, however you will soon discover that most of them are very large, and require an immense number of parts. This may discourage LEGO fans to even try building a GBC. However if you examine them closely, you will see that all GBCs are made up of smaller modules. Each module handles the balls in their own unique way, then passes them on to the next module. So it is quite possible to build Great Ball Contraptions module by module, as your skill, experience, and LEGO collection grows (all images by Josh DaVid).

In fact, you can build single-module GBCs, that feed the balls back to themselves, and thus creating a closed loop within a small space. Because these small GBCs don’t require so many parts, but are still fully functional, they are a great way to experiment with GBC building ideas. You don’t even need LEGO Power Functions elements to operate a small GBC, instead, you can make them manual. Once you build a couple of modules that you are satisfied with, you can open up and connect the loops to create a larger GBC, and even add Power Functions.

To help you start out with small, sell-containing GBC modules, LEGO fan Josh DaVid created a series of examples and tutorials that you might useย for inspiration. Josh also demonstrates how each module can be operated by hand, or attached to a LEGO Power Functions motor. I also like the tasteful designs and color-schemes.

The basic idea of Great Ball Contraptions is to keep the balls moving, and as you can see in the videos above, there are many ways to roll, lift, throw, and guide balls through a path, and you can use LEGO elements in pretty much unlimited ways to create the action. As long as the piece can roll, push, flip, or drop the balls, they can be incorporated in your layout. While here our focus is on smaller modules, Josh also has a series of tutorials on larger units with more detailed instructions on his YouTube channel.

If you plan eventually to connect smaller GBC modules, it is a good idea to build them in a compatible way, so you can easily open the loops and pass the balls from one module to another. While you can certainly establish your own system for connecting modules, you might also want to familiarize yourself with the Great Ball Contraption Standard, established by LEGO fans to be able to connect smaller units from different builders at LEGO shows and conventions. This way your modules are ready to play well with those built by others from the start.

Great Ball Contraptions are an excellent way to take the LEGO hobby to a more challenging level, while still having lots of fun. And as demonstrated here, you can start small, and build up your modules, as your skill level and experience grows. What do you think? Have you considered building your own GBC modules? Or did you make one already? Feel free to share your own experiences and tips in the comment section below! ๐Ÿ˜‰

And you might also like to check out the following related posts:

{ 24 comments… add one }
  • Tony March 22, 2017, 11:17 AM

    These look doable. I think it would be great if lego would release a GBC starter set. It doesn’t have to be big, but it would have all the elements needed to make a GBC. Balls, gears, and a basic track. A motorized option could also be available, and a book with suggestions.

  • brickmaster March 22, 2017, 11:30 AM

    I always wanted to make one of these, but the big ones look so expensive. Starting small is definitely a good idea, and a lot more affordable. Did anyone ever submit a project like this to Lego Ideas? If it is good, I would support it.

  • jabber-baby-wocky March 22, 2017, 2:34 PM

    Nice idea with going small for GBCs. I could see this being a great project. I looked through Josh’s youtube channel and he has many great tutorials.

    • admin March 22, 2017, 4:03 PM

      Yeah, he has some great tutorials. ๐Ÿ™‚

  • gid617 March 22, 2017, 9:41 PM

    I’ve always been kinda daunted by GBCs myself… that, and the fact that I only have one basketball. ๐Ÿ˜› They look like they’d be great fun once they’re done, but I’ve never been much good at putting together that kind of mechanical stuff, though I do like learning about it. Plus of course there are always so many other things to build! But if I ever get in the mood for a GBC this is something I’ll come back to. Starting off with small modules is a great way to go.

    • admin March 23, 2017, 12:12 PM

      It is worth learning how to build GBC’s – at least on a smaller scale – because you can use GBC techniques in regular builds as well. I know you are mostly a castle/fantasy builder, so consider things like a medieval watermill, which is basically nothing more than a GBC carrying translucent studs instead of basketballs. ๐Ÿ˜‰

      • gid617 March 23, 2017, 3:44 PM

        Good point! Functionality in a MOC is always neat although it’s not something I do often – usually I don’t have the time, or the skills, or it just doesn’t make sense to spend hours adding functionality to something that will be torn up the next day. But some of my builds stick around for longer than that and as you point out a GBC would be a great way to practice some of the basic movement functions!

        • admin March 23, 2017, 3:55 PM

          This brings to mind that adding something moving is really important for publicly displayed models. People just like things that do something, besides just sitting pretty. LEGO fans know when something is an amazing build, because we notice the intricate details, unique parts-usage, unusual building techniques, etc. The general public is much tougher to please. They like things really big, or moving, or both. ๐Ÿ˜€

          • gid617 March 23, 2017, 6:29 PM

            Yes, and I’ve noticed that it’s often the models that are brought to conventions and that sort of thing that LEGO fans spend extra time on to make functional. I’ve never been able to do that yet (display MOCs, I mean) because of where I live… which means that the reward for me of doing a functional build is having to video it afterwards if I want anyone else to know. haha ๐Ÿ˜›

            • admin March 23, 2017, 8:15 PM

              You should start your own LEGO convention. I bet it would take the country by storm. ๐Ÿ˜‰

              • gid617 March 24, 2017, 7:10 PM

                ๐Ÿ˜› I will admit that something of the sort has crossed my mind (well, not quite so ambitious as a convention…). But our family houses the only TFOLs/AFOLs I know of in all Chile – well, of course I’ve met kid here and there who plays or has played with LEGO, but no dedicated fan. There probably are some, but they’d likely live closer to one of the big cities, not out in the country like we do!

                • admin March 24, 2017, 8:24 PM

                  I don’t know how things are in Chile as I have never been there, but how things usually start out at other places is that a local LEGO fan does a few exhibits. Like they may do a Christmas display at their local library, toy store, school, museum, church, or something like that.

                  It will be pretty obvious if the display is popular as people will ask about it, talk about it, etc. Other display opportunities will likely come up as well. Some of the people who see the display might get curious enough to facilitate a live event, and get together for some fun LEGO related activities, or invite the LEGO fan to be part of a larger event. This brings more exposure.

                  If people are interested, they may start getting together once a week or once a month to play together, build together, do more events, etc. That’s how a club usually start to form. If the club meets certain criteria, they can also get support from LEGO, and become an official LUG. It is usually the larger, more established LUGs that organize conventions as it takes a lot of time and effort to do something like that. But smaller events even a single LEGO fan can do. It’s sort of like missionary work, just in a different niche. ๐Ÿ˜‰

                  • gid617 March 27, 2017, 9:32 AM

                    ๐Ÿ˜€ Thanks for the tips! I’ve often considered asking the nearest LEGO store if they’re interested in a fan-model display, but they’re pretty far away and it’s been like two years since I was there last, so I haven’t asked yet. However, I’ll keep an eye out for other places where there might be an opportunity! (One big deterrent though for me has been the thought of having bricks tied up for much time… ๐Ÿ˜› But my collection has been expanding so I have less trouble leaving certain MOCs around for a while.)

                    I actually did display one MOC in various churches as we traveled around the US a couple years ago, but of course that’s an opportunity that doesn’t often repeat itself! I have a great idea for a 3D map of Chile next time though… ๐Ÿ˜‰

                    • admin March 28, 2017, 1:20 PM

                      That’s a good point about the display MOC tying up your collection, so it might be worth focusing on smaller events. I would love to see that map! I want to get into mosaics later this year that are somewhat 3D. ๐Ÿ™‚

  • Dry Bones March 23, 2017, 2:05 PM

    I’ve never really tried to build a GBC section before. I just watched what other people had built work. I think a stater set would be nice, especially for me because I don’t have any LEGO soccer or basketballs, or any other type, really. But I do have power functions ๐Ÿ™‚

    • admin March 23, 2017, 2:20 PM

      You can actually use other small balls too, not just the soccer and basketballs. The Bionicle balls work well also as they are the same size, or you can just use non-LEGO balls. Gumballs maybe? ๐Ÿ˜‰

    • Dry Bones March 23, 2017, 5:42 PM


  • TheBrickLot March 23, 2017, 8:50 PM

    Israelis are always so creative when it comes to inventing! I love it!

  • grizzbrick March 23, 2017, 11:24 PM

    I’m surprised no one has mentioned Planet GBC yet:


    It’s a great site with a lot of module examples, many with building instructions. For the record I have no affiliation with Planet GBC other than just finding it a useful website.

    • admin March 23, 2017, 11:40 PM

      Looks like an interesting site and great resource. Thanks for sharing! ๐Ÿ™‚

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