You can build a Raspberry Pi case from just about anything. Instructables user sandshock shows off an incredibly simple but fantastic-looking case built using just a piece of a oak and about $10 in parts.
While some mild woodworking is involved, the beauty of this case design is that pretty much anyone can do it with minimal tools. Using a few parts picked up from the hardware store and a power drill, the case can be slapped together pretty quickly. The end result looks great, protects the Pi, and doesn't take much work to make. Head over to Instructables for the full guide.
Oak Raspberry Pi case for under $10 [Instructables]