If you want your kid to be creative, you can teach him or her about Leonardo da Vinci geek-style by building this weapon of mini destruction, AKA da Vinci Catapult. Jonathan Liu of Geek Dad built one:
The kit, which includes everything you need to assemble and fire the catapult (except for a tape measure), takes roughly an hour to assemble and then can be used to launch a small clay ball or other small objects. It’s a combination of two designs drawn by da Vinci in the Codex Atlanticus, using bent wood rather than twisted ropes for the energy needed to launch the projectiles.
[Source]