A pinhole is the basis of photography, a sensitive area in a black box with a hole and you have a tiny pinhole. No photosensitive cells, no viewfinder, no lens. Cardboard shoe box to keep everything is good at creating pinhole. For my part, I use a Zero-image, produced in Hong Kong.
The Magic of Pinhole resides in the tiny hole that serves as a lens. As the amount of light is minimal, long exposures are an absolute necessity and movement becomes blurred, only static object remains sharp.
As well, this system of shooting is a diaphragm f: 325, so the depth of field is very close to infinity.