On fredflare.com they offer this Japanese kit that lets you create your own 35mm pinhole camera.
Assemble the heavy cardstock pieces without any cutting or glue, add a roll of 35mm film ‘n snap away. Item can be used again & again.
http://www.fredflare.com/customer/product.php?productid=1977&cat=103 - via Retro To Go
Or you can make a pinhole camera from a matchbox, which I've gotten some great results with.