A vortex cannon made from a Kirkland brand cup.

You need:
a cup with a 22mm hole in the bottom
2 size 32 rubber bands (yes, they have sizes! Other sizes would work, to varying degrees).
a 7" wide plastic bag. The one I used was 10" long, which is much longer than needed but commonly available.

Assembly video: https://www.youtube.com/watch?v=EMsWm7837aE

Category: Mechanical Toys