"I'm leaning toward catapult because I don't think trebuchets would scale down as well because the counterweight would be limited ..."
My friend built a one to two foot trebuchet and it worked reasonably well, although he had to use lead weights to make the counterweight powerful enough, so your concern is not invalid.
My friend built a one to two foot trebuchet and it worked reasonably well, although he had to use lead weights to make the counterweight powerful enough, so your concern is not invalid.
Trebuchet at that scale wouldn't need some of the more complex parts like a winch unless you wanted to add it. You could build it and manually reset it at that weight and size. Also its a more elegant display of physics.