Up or down scale, do it yourself with a trebuchet kit, Legos or plans.

Want to take a ride?

...I was browsing through a history book in the library and came across a story about a king whose castle was under attack. The king needed food for his people and offered one of his sons as a hostage to facilitate a cease fire and open negotiations. When the negotiations fell apart the attackers put the king's son in a catapult and hurled him against the castle wall. A sad page in history, but it got me thinking about what it might be like to ride a catapult. Remembering the first catapult I built, and being inspired by Walt Disney (He loved trains, and built the first rideable miniature trains) I set out to build a catapult scaled to throw me 40 or so feet through the air to land safely in a river. I set out to build and ride a replica of an ancient throwing machine.

I settled on a design called a trebuchet.

Don't try this one at home, kids.

Downscale: the world's smallest catapult (I'm guessing about 3 mm long). If we had these, a football field would be a small step.

Another picture here.