Locking Ball and Socket Mount
This file describes a parametric ball and socket mount that could be used to position a small, lightweight object at a specific angle (e.g. a touch-on LED closet light that is aimed at an object of interest).
The socket has screw holes for attaching to a substrate like a wall or door. Objects could be attached to the ball mount with Velcro or adhesive.
It uses a 10-32 thumbscrew to apply pressure to the ball to keep it from moving, with the extant hole drilled with a 3/16" bit.. I am using McMaster-Carr Item#: 91185A386
The file has an option for a dimpled "golf-ball-esque" look that makes it lock into place easier.
2015-08-17 - Updated, added a support flange underneath the set screw to make a stronger design.