I have rebuild an old Agfa Click I camera into a pinhole camera. I removed the plastic lens and placed the pinhole on the outside of the body but behind the original shutter. This camera and the Agfa Clack can be converted easely into pinhole cameras. The Clack has a slightly curved filmplane and a negative size of 6x9 cm. The Click I has a negative size of 6x6 cm. Both use 120 rollfilm.
I loaded it with Fuji NPC 160 rollfim and went into the fields on a very hot day for a testdrive. I found some cowes willing to pose for a few pictures. I placed my camera in the field and let the cows come close.
They are very nosy animals....
Exposure time was about 30 seconds on the middle of the day in the full (and hot!!) sun. These were the results:
Check the Pinhole Photography & Cameras Group on LinkedIn for more info on pinhole cameras.