Here's my admittedly shabby case for my pi. Loosely inspired by Pibow. When I saw that case and how it was made up of layers then I thougth "Hey, My workplace has lot's of extra cardboard. I could try something similar and have a free case".
My job is fairly laid back most of the time (I make Honeystix for those who care). So I brought my pi to work and set off. what I ended up with was several pieces of cardboard elmer glued and duct taped together. Hence I'm christening it Red Green mark 1. Doubt I'll ever make another though. My goal was just to have some form of protection so that I could feel comfortable leaving it on 24/7 and not have to worry about water/objects dropping on it.
http://smg.photobucket.com/albums/v497/ ... %20mk%201/