Flyby8, I made mine from parts in the shop. The drum is 3/4" diameter as is the bearing, but I'd prefer a larger one. A drum with 60 or 80 grit works well, finer grits tend to cut too slowly and burn. I think something like this is commercially available, maybe Woodcraft or Rockler woodworking tools. The picture shows mine chucked in the drill press, which I sometimes use in place of the router table. You need to space the template away from the balsa to be trimmed by about 1/4"