I tried a pinhole shot using my DSLR body, minus lens.  Of course, all had to be in manual or the shutter would not work.   This was very, very unrefined with aluminum foil over the front w/pinhole.    These were very soft images, out of focus but in a way more like  "extra soft" more than a focus problem.   It worked.  I am sure this could be refined with a tube or something for "lens" but it neglects the pinhole concept of film in a box.        Tom.