1. Any closeable container. I
prefer small plastic bottles, film canister, even those plastic Easter
eggs. But there is not "wrong" container. I have heard great
sounding shakers made out of soda bottles, cool whip containers, laundry
detergent bottles etc.
2. Any small hard substance. I prefer
pop-corn, beans, rices etc. but you can also use sand, gravel, BB's,
clean kitty litter etc. half the fun is experimenting.