While I'm not going to purport to copy the likes of Shi Guorui (http://www.slowlight.net/blog/?p=79) I am interested in the feasibility of such a concept. Could it really be as relatively simple as constructing a light-tight box with lumber, blacking-out materials, etc.? And how could I calculate the distance from opening to viewing surface? I may construct this as a simple viewing room where participants can trace the image they see, or have large sheets of photo paper tiled to make a large photographic image. Any help is gratefully accepted.