Like my kids need me to make things that will poke thier eyes out. My son was studying ancient rome, so we made a trebuchet (high tech catapult). It is just a few strips of wood glued together with a stack of washers used as a counter weight. I toyed with the idea of a video to show it shooting, but I didn't bother. It has a sling made of string and a pouch of denim. It will chuck a ping pong ball about 10 feet. We found plans online for the trebuchet and made one that was substantially smaller. We used centimeters and millimeters instead of inches (1 inch = 1 cm or 10 mm). The plans that we used suggested that an 18 inch trebuchet called for about 3 pounds of wieght on the end of the swing arm. We used less than half of a pound and it worked great. I guess a bigger one could chuck larger items farther, but my wife has informed me that should anyone sustain life altering injuries with the trebuchet, that my second wife can explain to me how bad an idea building this catapult was.