I have found many excellent sanding blocks in this site, but ever tried to sand a round object with a flat sanding block? Frustrating, eh? so I designed this simple device that uses a sanding paper strip which is held in place by passing it trough a slit and then secured with a clip. The dimensions are for sanding small objects, but it could be scaled if necessary I guess. It is also very useful for sanding objects in reduced spaces.

I have added a customizable version: https://www.thingiverse.com/thing:2942438