The following is an article that originally appeared in Popular Mechanics Photo Handbook, 1948 edition, pp 112-113. It was written by Walter S. Marsh.

The only thing they don't happen to mention is that you still have to get the dark. As I mentioned elsewhere, it's not easy to make a room dark enough for photo work. You'd be surprised.

Still, I think this is an interesting project. If I still did enough darkroom work to make it worthwhile, I'd build the thing myself.