My disc sander is indispensable for both quick wood removal and final smoothing. I got tired of changing and wasting discs every time I needed a different grit, though, so I made one disc out of two. To make the dual-grit disc, I lay two 12-in. discs together, one coarse and one fine grit. Then I cut a 6-in circle out of the middle of them with a utility knife. This gives me two sets of dual-grit discs and nothing goes to waste. When I mount them to the disc sander, it's just like putting the doughnut hole back in the doughnut.