Haven't looked for the *answer*..............
I have some sanding drums that I bought REAL CHEAP at the hardware. They are 3/4" or 1" diameter and I bought a bunch of sleeves in different grits. I have a circle template, and I use the drums to get to the finished size. You can turn them with your hand, you don't have to have a drill for the final fitting. Scroll saw to about 3/32nds from the line, then sand.