This is a Sander Block/Tool I came up with to help sand cosplay helmets.

It has a number of sides for all different shapes, large radius,small radius, flat and curved surfaces. As well as another version with a finer tip.

You should get at least 6 strips of 1.5 inch wide from one sheet of sandpaper that is 9 inches wide. Or cut into 4 strips if you want to fold over the sides if you need a 90° edge for bevels etc.