pin hole cameras

I have recently started to make some pinhole cameras, I have never made any before but they are quite simple.  I have done quite a few samples and had little success, however today I have managed to get to grip with long the exposures should be in certain conditions; for example depending how large the aperture is, how sunny it is and where the camera is pointing.  The results are quite ghostly but I like this. There is one I especially like where there is little detail given but u can see the shape of the buildings and landscape.  Eventually, I want to make a pinhole camera which has 6 different apertures.  All facing in different directions; up, down, north, east, south and west.  This will allow me to preserve all areas of my site at once.