The front of the book camera. The rubber band keeps all the insides from falling out. The wood stick turns the film. Inside the square cutout has a piece of thin metal with a small pinhole. The square flap is used to open and start the exposure.
The second pic shows the view of the film in the camera. This can be adapted to make an exposure to your liking. Maybe keep it basic like normal 35 or cut a perfectly square hole to give it a Holga feel, or experiment with panoramic or the shape of batman.
The last image hows the back of the pinhole and the square chamber with the film at the back. Cut it with a very sharp xacto.
idea by Sreiny