I recently went into an actual physical store, and decided to pay for my purchase with exact change. When I took the above item out of my pocket, the clerk asked me what it was. I said it was a "repurposed film canister," which elicited only a blank stare. I instantly realized that this young teen had absolutely no idea what a film canister (or film) is, so I explained that it was a little "doodad" that keeps change from rattling in my pocket. She smiled and said "That's cool."
I have a bunch of them around the house, storing spare buttons in the clothes closet and screws etc on the workbench and seeds in the garage. They will outlast me; I need to decide which of my young relatives will be lucky enough to inherit them.
Addendum: scroll down through the comments to find a link about how to build a film canister rocket. And this link offers a comprehensive look at film cannons (hat tip to reader chemsolver).