Great Ball Challenge (GBC)/Marble Machines


Great Ball Challenges (GBCs) look to be a great Makerspace activity:

  • standardized input and output (ball size, entry/exit height)
  • does NOT have to be lego(!)
  • fun to watch from one module to 100’s
  • scalable: can be as simple or as complicated as you like
  • great skill builder: so many different ways to move the balls around (conveyor belts, elevators, vacuums, magnetic levitation, blowers, catapults, swings, Archimedes screws, …) and detect them (purely mechanical, discrete electronics, micro controllers, computer vision, …)
  • can be taken to events

And most importantly it looks like fun!

Some inspiration:

Here is an interview with the creator of above, Lego GBC legend Akiyuki.

And a marble machine:

Some starting references:

  • Planet GBC- getting started
  • GBC Standards
  • beginner Lego GBC designs - suggest using these ideas as inspiration rather than designs to build exactly; lots of these builds use parts from many different kits. Also, if we’re not being Lego purists, can reduce parts counts by using non lego parts; eg cardboard for smooth surfaces.
  • there are lots of marble machine resources, but it seems that the marble machine world doesn’t have a “standardized module” community.


  • keep the depth to 11.5" or smaller; this is just to make it easier to display on standard book shelves.

Useful Tools

Linkage simulator. Can help to design things like this: