After being dissatisfied with both the Sorby and Monster inertia sanders (I may be doing something wrong - my technique may be off, but I have no one around to compare with) - I decided to make my own. After only a few uses, I found the 'store bought' ones didn't rotate as well as they did when brand new. I based this on a couple of designs I found on the 'net - using two ball bearings, spacer, a 1/4" bolt and a nylon lock nut and a piece of alder finished with BLO - haven't used it yet, but will let you all know if I have the same problem with my home made one. Oh, the 1/2" foam is from a sleeping bag pad, 2" in diameter, backed with plywood and has some industrial velcro stuck to it. Getting the thru-hold and 'mortises' for the bearings was made simple by using my OneWay Drill Wizard. Figure it cost me almost $3 to make. Mike