This robot has no purpose except to juggle steel ball bearings. It’s impressive the simplicity of the design, mixed in with something most humans can’t do.
Nathan Peterson built a robot that is capable of juggling 7, count ’em SEVEN steel ball bearings. Using two 3-D printed arms with electromagnets in the bottom, they alternately spin around and throw the balls up into the air. It looks like it could go on forever, but luckily, it’s just as fallible as humans, and the balls hit each other and messed up the whole rhythm.