Simple Solidworks 2014 model that you can Adjust the inside Volume and Wall thicknesses.
Check out this Video for more info:
http://youtu.be/jgnN0x6gR8U
If you need and special size case and you do not have solidworks, please add a comment of the size of box you need and what it will be used for.**

1)Adjust size of box in solidworks
2) Export file to STL
3) Print File
4) thread 1.75mm filament for hinge, leave 10mm excess on both sides
5) Use a heat gun or lighter to heat up filament
6) Press filament with a knife to the side of the box to fuse together
7) Upload you design for other people to use ;-)