I used this tutorial from Francesco Caponni found via flickr.
It's really simple and with the film and scrapbook paper I spent about $12 for 2 cameras.
I suggest you print on sticker paper. We didn't and it was a pain to use double stick tape to attach the patterns to the cardboard. After following the tutorial I covered mine in scrapbook paper because if it isn't pretty then what's the point?
I hope we'll test them on Thursday because Brian's coming over for dinner!