Needed a simple but reliable battery case for kids to use, so I made one to have the features I was looking for:
-Easy to print (so support, no raft needed)
-Screw holes to secure to project
*11/05/15 Updated - Minimal update to give the sides a bit more support. Also added very small (1mm) 45 degree indents in all edges to help pry finished case off print bed**
Uses strips of metal zip ties (no sharp edges) to make the battery contacts. Easy to cut with tin snips and easy to bend into shape with some needle nose pliers.
Small grooves along the contact holes allow for cables to be inserted much like a breadboard for easy connections to your projects. The batteries press against the contacts pinning the cables in place.
Use a paper clip or another piece of zip-tie and a couple of small screws to make an easy ON/OFF switch, or add a jumper between the two for a traditional battery pack (no soldering!)
Very simple design, hope you can use it or improve upon it. Enjoy.