I've made a couple small items. A quarter tern mount for my Garmin eTrex, most of the ones out there tend to twist around the mounting screw so I made mine clamp around the humps on the battery cover.
https://www.thingiverse.com/thing:6036724

Other one is a gopro mount for my Camelbak, this way I don't have to wear a chest harness or anything additional. My mount replaces the sternum strap clip on one side.
https://www.thingiverse.com/thing:5424730