It works just like a real catapult would have, a twisted rubberband, a winch to prime the arm, and a lever to let it go.
This one is operated by dwarves.
This was partly inspired by zcerberus' trebuchet and Ecclesiastes' catapults.
Any comments or criticism welcome!
p.s. I can make it more powerful by just twisting the rubber band one more time, I will probably post another video of it in action after doing that.
Edited by soccerkid6, 07 June 2013 - 12:40 PM.