If you have some old speakers lying around, a good way to say goodbye to them, is making a Corn Starch Monster on them.
Maizena (corn flour) or Potato Starch works well. Mix it with water until it becomes a liquid base.
Then pour the mixture on the speaker and start it on a low frequency, around 20 Hz. The Starch will then start dancing.
The water and cornstarch mixture is a non-Newtonian fluid, and this means it behaves very oddly. You can pick it up, and if you keep moving it about so it’s under stress, it stays solid. But as soon as you let it rest, it goes back into a liquid.