Anything you strike, anything you shake or rattle, or just anything that can be picked up, and you can create a sound.
I learned my business in the theater and in television, particularly working with the actors. You can learn much more in the theater than directing a movie, because then you have no time when you are shooting a movie to really work with the actors. You have to learn this craft somewhere else.
If it doesn't come through the Internet, it's not really compelling to me.