scarlson 

I used to! Powered by all manner of things, from ganged rubber bands (first iteration) to inner tubes to trampoline springs. I also had several trebuchets and mangonels, one of which was wrist-mounted like a slingshot but more accurate. I was an absolute terror to my neighbors as a child. This was the king of them all, made from a truck leaf spring, and the only survivor from my collection. It was (and still is) slightly scary to shoot, but the trigger's a rolling-nut good for 500lb I think. The cranequin could pull that as well. The first bolts/quarrels I fletched up were too weak and split down the middle when I shot them, both halves taking diverging trajectories with a mist of splinters flying generally downrange! These days I shoot with Harvard Archery Club. They "get it" when it comes to homebuilt bows.