This is a slim case for the iPhone 5 that has a working geneva mechanism on the back. It's something fun to fiddle with, and always draws curious questions. I don't like bulky stuff in my pockets, so it only adds 3mm to the back of the phone.
Updated 3/16/2013 to provide a better fit around the phone.
1) Print the case & wheels. I used PLA, 0.2mm layer height, 30% infill, 1 extra shell.
2) Drop the wheels into the case as shown in the photos.
3) While holding things in place, make sure the mechanism turns smoothly. If your top surfaces are rough, you may need to smooth them out. If your first layer is thoroughly squished onto the build platform, you may need to trim the edges of the wheels (especially the tips on the star wheel).
4) I find it helps the action a bit if you rub a pencil around the inside of the "ring" on the case and the outside of the "moon" on the moon wheel. The graphite will help keep things from sticking.
5) Pop your phone into the case to hold the wheels in place. I find it's easiest to slide the top edge in first, and then press the bottom into place.