Raspberry Pi Cardboard Cases
These are a couple of papercraft case designs for the Raspberry Pi. They were created using Inkscape and can be edited in that for making your own customised designs.
They are designed to be printed on thin card (approx 200-250gsm), scored on the folds, cut out and glued using a card suitable glue such as UHU.
Raspberry Pi Zero/Zero W
These cases are designed to fit a Pi Zero or Zero W with the GPIO headers fitted, and to be openable to allow insertion/removal of the Pi. The Pi needs to be fastened inside the case, I recommend Blu-Tac or similar, as a simple reversible option.
Plain Box Case
A simple box case from which the others are derived.
BBC Micro style
Classic 1980's computing in a mini package.