30' Trebuchet

A Trebuchet is like a catapult that uses weights instead of a spring to launch an object. The guys over at Supersoda.com just completed construction on a very large one - 30 feet to be precise. They have used it to launch all sorts of things like water balloons and cows at King Aurthur and his knights.

30 Foot Trebuchet.

If you want a less ambitious project, check out this page with some really cool hand-held trebuchets and catapults that you can build.