eli5: how do paint rattlecans work?

Question

eli5: how do paint rattlecans work?

In: 16

Answer 1

The thing inside the paint can that makes it rattle is a child’s tooth.

Just kidding. It’s a (usually rejected) ball bearing. Its only role is to make noise so you know you’re sufficiently shaking the can. Spray paint really needs to be shaken well for best results. Making the can satisfying to shake by causing it to make sound reduces consumer complaints about crappy spray paint.