Don't forget the tennis ball rocket launcher. You would can-punch a hole in the bottom of one and leave the top alone with the pull tab removed, tape two more cans on top of it with their top and bottoms cut out. I think we would put a little rubbing alcohol in the bottom one and light it through the can-punched hole. The tennis ball would fire out of it like a bazooka going 100-150 ft. up in the air.
That sounds like it would be fun.