The good thing about digital cameras dominating in popularity over film these days is, many photographers have ditched their film equipment, therefore all the items needed can be found for pretty cheap from thrift stores, eBay, Craigslist, and local photo schools.
The pinhole camera has been a classic DIY project for students discovering photography for many decades. If you want to get a deeper appreciation for the basic DNA of a camera, build a pinhole camera. Pinhole cameras are bare-bones cameras; they consist of a black box, a place to put photo-sensitive material, and a pinhole-sized opening that projects a faint image on light-sensitive material. Stripped of the bells and whistles, all cameras—film and digital—follow this design. Some (OK, almost all) cameras are more advanced. But DIY is making a comeback, especially among millennials, so, let’s make a pinhole camera!