I was told this might be a good place to ask.
I'm looking for a slipring or commutator to go around the axle to my wheelchair wheels. The catches are, it needs a 1" center hole (to go around the axle nut), nothing can break if the wheel's removed (that's easy, just push a button) and the body's put in a car trunk, and it only has about 10mm clearance axially. On the plus side, it only needs to carry a hundred mA, its radial clearance is something close to two feet, and my maximum speed is around 75 RPM. Four conductors would be nice, but I can live with two. Does such a thing exist for a reasonable amount of money, perhaps in the model-making or robotics communities?
I have an idea about making one (per side) out of a CD-R, some alternator brushes, and some sheet metal, if a pre-made one can't be found. I figure I'll put the CD part on the wheel, to keep its angular momentum down.