Galaxy S4 Belt Clip for Otterbox Defender
Edit: The _reinforced version adds some reinforcement to the back of the clip.
The belt clip segment of my Otterbox Defender kept breaking. I wanted to be able to print replacements as needed.
I took http://www.thingiverse.com/thing:216979 and modified it so it would fit around the defender case, fixed a few issues with the clip on the side (including reinforcing it significantly), and added a belt clip based on http://www.thingiverse.com/thing:30244.