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)
tape
a pin
light sensitive paper or film (I used Polaroid 300 available on Amazon.com)
a dark dark room
rolling pin
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.

Step 2: The Pinhole

Make your pinhole and "lens cover". I used three layers, actually, of duct tape, because, as it turns out, duct tape isn't so dense. It wasn't a big deal though.

Step 3: DARK ROOM

Now you need to go into that dark dark room. When you're in there, you have to put your film into your camera and tape it in there so it won't move. With the film I used, I had to make sure I was putting the right light sensitive part towards the light and not the back of the camera. If you're using the same film I used, the trick is finding the bump at the top of the film. Finding that with your fingers will tell you that's the light sensitive side, and its the top of the photo, which needs to go on the bottom, because your image will be flipped as physics works its magic.

Step 4: STILL DARK ROOM

Close up your camera. With my little tin, there were suggestions to tape it up and make sure no light would get in. But, in a trial run, I did, and I tore the whole thing to bits trying to get the film out. So I just went without.
TIP: the way to know which is up and down and whether or not the film is facing the right way is to give yourself a little tab on your lens cover.
After it's sealed you can take it just about anywhere.

Step 5: Exposure

Depending on how much light you're using to expose your film, you'll need to do some mathematics on how long your exposure should be. Mine was inside, and I have florescent lights. And with the ISO of the Polaroid 300 Film, and the light meter tested with my point-and-shoot, I came up with 50 seconds. There is something fancy about figuring this all out, but in reality, I just had to try one and see how I liked it. What really matters is how in focus you want the shot to be. I was pretty well pleased with the outcome.

Step 6: BACK TO DARK ROOM

Once your film is exposed, you've got to go back to the dark room and bring your rolling pin and flat surface with you. [I used a cutting board. Also, I used my bathroom with a towel stuck under the door.]

Take the film out, or off or however you have it situated, and using the rolling pin, you've got to break the seal of developing liquid at the bottom of the film and role it over the exposed piece of film. This is really how Polaroids work, ya know. I know its a little bit on the resourceful side, but, its still cool to make a picture with a tin and a rolling pin.

Once you've done that, you are ready to go! Your film can be untaped from wherever it is, and you can shake it just like you would a normal one. You'll get some pretty neat images. GOOD LUCK!