Medium size Trebuchet

Cathy, the program director, was looking for something neat to do as a lobby activity. Something the kids can do during free time. She suggested a catapult.
What you want is a trebuchet, I said. A catapult uses a throwing arm under torsion. It needs to be hauled back to lock and load. A trebuchet, on the other hand, uses a counterweight which could be unloaded so that kids operating it don not have their teeth knocked out by a misfire. I got the job. 🙂