Intro: Pocket Wire Crossbow
This tiny crossbow and the bolts are made out of 2 things; steel wire (a little thinner than a paperclip), and a rubber band. Although the crossbow is smaller than my palm it can easily hurl the bolts across my house at a good speed. Although one of the downsides to it's size is firing it is really hard.
I will try to make an instuctable on this sometime.