McMaster Carr is great! You can go the conveyor route which is better than rolling pins, or you can actually buy individual roller drums (they even come with the requisite axles). I went this route. Used some aluminum "C" channel for the side rails. Bolted everything down to a piece of plywood with some of that black perforated/nubby rubber matt on the bottom. Can customize for wheelbase. With a solid base it doesn't move underneath you, and the base/matt absorbs a lot of the vibration, reducing the noise.