I wasn't sure which topic to put this in. Could have gone into "Cameras" or "Lenses" or into the "show your camera" threads. I think it deserves its own.
I just built this. Took me about an hour of tinkering. So there is one case for its speed. (I really should be working on other things, but I am easily distracted.) The lens is a Barco Delta HD-6C ML. It is an 8 lb. monster I liberated off one of those old three lens video projectors. And, yes, I still have the other two. These have been sitting in my garage when I rediscovered them over the holiday. Looking at them I wondered if it could just cover 4x5. So, today I finally dug out a Crown Graphic Graflock back I knew I had lying around. A couple pieces of birch ply and some screws... voila! The lens already has helical focusing and almost no depth of field. Set up as is, it has a focus between 3 and 30 feet. I imagine using a 1/2" ply would give me an infinite focus, but that is for another day. I am guessing the f-stop around 1.2 and 1.4. I plan to use it for paper negs at some point. I wish I had more time and less to do.