If you want to build something that will last a long time, you are probably better off using something like hard plastic, or at least new rubber. If you have an old belt driven device that no longer works, it's probably belt degradation. It doesn't even have to be that old. I'm currently repairing a tape deck that was built in 2003, the belts are completely disintegrated into oily goo, the only evidence that there was ever belts at all is the residue left on the wheels.