Modular parametric ring building kit.
Instead of using magnets, this uses my pin connector library. I also redesigned IWorkInPixels's ring body to be slimmer than the original. Edit the ring size variable in openscad to make a ring to fit your finger. I've included a ring that is 16mm in diameter and one that is 25mm in diameter (I have fat fingers).
I've also included some sample add-ons. Use the included negative to cut peg holes in the bottom of any thing or better yet use the pin connector openscad library. Connector is also compatible with my dalek body parts: http://www.thingiverse.com/thing:15253
Go ahead, you know you want my head on your finger.