In my neighborhood growing up it was kind of a right of passage to make a tennis ball cannon. As I remember it, you taped three or four soup cans on top of one another with the middles and tops cut off of all of them except for the bottom. I guess we must’ve used duct tape or something pretty strong. The tennis ball had to fit tightly. And force down to near the bottom.

You used to punch a little hole in the bottom cam with a nail and then spray some lighter fluid in it because somebody’s dad smoked and lit the cigarettes with a zippo lighter. You then hold a match the little hole where you sprayed the lighter fluid and it would ignite.

These would easily shoot a tennis ball over a house and made a satisfying whop sound.

I certainly made potato cannons later in life and those were kind of unreal. I made one that would regularly shoot potatoes to supersonic speeds making a loud crack, but it all started with the humble tennis ball, cannon, soup, cans, duct, tape, and Ronzel lighting fluid.