I made this from cardboard, old velvet jeans (for light-tight cover). The shutter is made from the back of an old 35mm camera. To start an exposure, you slide it down the plastic rails (barely visible). The pinhole itself is made in a foil shim.
Thanks to the large format and shallow depth, this camera is extremely wide angle and light falloff is severe.
image from svofsk on Flickr
Making your own camera is fun stuff, thanks for sharing your project!