Glue up a bunch of disposable sanding blocks and stop fussing with reloadable store-bought blocks. When the sandpaper’s used up, toss them and make more. A 2 x 4-ft. piece of 3/4-in. medium-density fiberboard (MDF; $8 at a home center) will make a lot of medium and fine sanding blocks. Saw the fiberboard into 2-1/2 x 5-in. blocks. Then space the blocks—six per sheet—on sandpaper coated with spray adhesive. With a sharp utility knife, trim the sandpaper flush with the blocks. Write the grit size on the sandpaper with a permanent marker. It’ll be easy to find the grit you need, and the ink won’t stain your wood.