This is actually a really simple process and once you've done it, you can do it forever. Pinhole cameras can be made out of any canister that is dark inside. I used a little food tin, and because it is shiny and metallic, i had to paint it black. I think I would suggest it of any canister used, though.
Materials needed for this project:
your canister of choice, preferably with a lid. (mine was a food tin with cardboard cover.)
black spray paint (the cheapiest kind, 97 cents from home depot)
light sensitive paper or film (I used Polaroid 300 available on Amazon.com)
a dark dark room
a hard flat surface to role on
Step 1: paint
Just go ahead and paint the inside of the canister black. I did two coats just to be sure and cover up all the shiny bits. We don't want ANY reflective surfaces on the inside of the camera.