Here’s a tip from tool inventor Bernard Kirschman. Cut short pieces of PVC pipe lengthwise to make contour sanders for convex and concave surfaces. (It cuts easily with a handsaw, saber saw or band saw.) If you like, leave a section of the pipe uncut for a handle.
Apply adhesive-backed sandpaper to the inner and outer diameters, or spray photo-mount adhesive on the pipe and apply regular sandpaper. You can match the PVC’s inner and outer diameters to rounded or curved surfaces and edges so when you sand the contour you’ll preserve its original shape. Make a few PVC sanders in various diameters and you’ll find yourself using them for all kinds of filing, sculpting and intricate fitting jobs.