I can’t take any credit for this.
Earlier this summer, I built a Rubik’s cube solver from a Lego Mindstorms set. I simply followed the plans for the Mindcuber design. It seemed to work quite well, but my Rubik’s cube had one face which was much stiffer to rotate than others, and the power available from the Lego motors was insufficient to reliably turn it. So it’s been sitting in my office for a while doing nothing. Today, however, Rob lent me a speed cube he bought from Amazon. It’s designed to take as little torque as possible to rotate, and has nicely chamfered edges so it doesn’t jam if it’s slightly out of alignment when you try to turn it. In the picture, the speed cube is the one on the left.
The cube-solver robot loves it. I’ve posted a video of it on the YouTubes at http://youtu.be/iDMrePmmNA0 .
The whole thing is a supremely pointless exercise, but it is rather hypnotic to watch.