I just came across this 4x5 pinhole camera I made some years ago out of mounting board, balsa wood and gaffer tape mostly. The pinhole was made from a piece taken off the black plastic inner envelope from a box of printing paper. The hole was made with a needle heated over a flame. The design was strictly make-it-up-as-I-go. I would do it differently next time but it seems to work OK. Here is a shot from the camera (FP4 in Rodinal). Direct neg scan. I think it gives a pretty sharp image for a pinhole.