This is a free cardboard version of a $50 crossbow, made from junk, designed to fire drinking straws. I designed and made this model myself, with my kids and we had great fun with it. You'll need a rubber band, a couple of wire coat hangers, a wine bottle cork, a couple of old ball point pen barrels and some corrugated cardboard. Free templates for the wood pattern can be found at dadcando
, where there are a few other projects that you might be interested in.