This vid reminds me a lot of when I was a kid and we were too poor to afford toys (and a very anti-gun father meant I wasn't allowed to even be given any from relatives and family friends) Soo.. I ended up making my own from a library book which showed me how to make a fully functioning rubber band gun out of cardboard and split pins.
This home made paper clip gun takes the rubber band concept and launches paper clips, which I'm guessing will sting and probably shouldn't be aimed at anyone's face (or any other body part for that matter!) but still made me smile. Cheers Ryan for the link.