This Make reader did a really nice job of building the three-cap Symet (a.k.a. a Trimet) from my BEAM projects piece in the latest Make (No. 6). His build is almost identical to mine, but his discharge time and the amount of spins he gets is a bit less. Mine got a pretty satisfying rotation on each charge. Not sure which value of voltage trigger he used. His is so neat and beautifully soldered. Mine was messy and I solder like crap. Maybe that had something to do with it. I had more weight in lead shot. Here’s a link to a few more Flickr pics, and here’s a link to a YouTube vid showing the little robo-top in action.
Here’s another builder’s bot. He ingeniously added little flange/fin thingies and it looks like a ball on the bottom (known in a BEAM trade as a motivator) to the motor axle. I’d like to see this one in action.