I was wondering, is it possible to build a running wheel? Like this one? (this one is used on the biggest trebuchet in the world, because there is no other way to lift the counterweight) I tried, but miserably failed - that "wheel" didn't move at all. Though, it would be great to have it. It's a nice replacement for a rotor block - only thing player should do is press autorun. It will probably generate quite a big torque, which is so needed for so many applications. So, maybe somebody tried as well and succeeded? It would be great to hear, how to build it!