This is a relatively simple but overcomplicated golfball cannon I built in the summer after I graduated high school before starting college (the first time).
For some reason, I decided I needed a "backup tank" of propane on the cannon, which in no conceivable universe would actually be needed. Really I just wanted to add bullshit to the gun.
This is a very poor quality video of me basically missing a piece of plywood with a golfball.