That's brilliant! I didn't think of using materials like Lexan, but I had on hand a 2.5" aluminum pulley with a flat face, to which I could paste circles of sandpaper. I found a suitable motor with the correct shaft size in a recycled materials store, and mounted it on a thick aluminum "L" section I had laying around, all mounted on a piece of good plywood, and ended up with this: The table there was thrown together with aluminum pieces on hand, I've since improved & simplified it somewhat. I wanted the whole thing to be as compact as possible, so I can easily shelve it when not in regular use. It works great! The RPM is on the slow side for a disc sander, but that mostly just reduces the chance of making a mistake or even injury. So yeah, that front sandpaper surface, gotta be flat, and centered. I should be able to glue a 4" circle of Lexan to the my existing 2.5" pulley face there, and shave the edges to get it centered/balanced.