Summary

These are printable parts for transforming any tin box into a pinhole camera. The shutter is designed to be operated with a finger on the sprocket looking part. The large surface area of the slide ensures that no light gets into the pinhole when closed. The design also features 2 versions of tripod mounts (with standard triptod thread) and 2 versions of flow through "light traps" to make the pinhole camera "self-developing" (the developing fluids can be poured directly into the camera and develop the film or photographic paper inside).

Shutter:
Fastened with 4 pieces of M3x10 bolts

Tripod mount 1:
For smaller box camera
Fastened with 2 pieces of M3x10 bolts

Tripod mount 2:
For bigger box camera
Fastened with 3 pieces of M3x10 bolts

Light trap 1:
Has a helical tunnel on the inside, not the most reliable, can have light-leaks, but very simple and easy to print does not need any support.
Fastened with 4 pieces of M3x15 bolts

Light trap 2:
Has a baffle on the inside, really good at keeping light out, but it needs support and the support is hard to remove from the inside (needs to be scratched with a screwdriver)
Fastened with 4 pieces of M3x15 bolts

The light traps can adapt a bottle cap from a wide mouth milk bottle to be extra sure that no light gets in under any circumstance.

When making a self-defeloping camera, a tin box with an internal coating is highly recommended, because the developing fluids cause corrosion to raw metal.
Also raw metal is reflective, so it makes light bounce around inside the camera and expose parts of the film we don't want to expose. If you can't get a box with an internal coating, just paint the inside with black spray paint.