A long, tortuous story. For the past year or so I've been building robotic camera stuff using Arduino boards and inexpensive servos. You can read some of it here: http://www.maxotics.com First a thermal imager, then a robotic panorama head like the gigapan (only built from the ground up). A couple of weeks ago a friend of a friend gave me some photographic equipment to sell (from her late husband), including some (whoa this is an expensive hobby!) 4x5 equipment and lenses. I'll probably sell before my 30 days is up here, but just in case I don't I'll post in a month.
While I'm here, I'm curious is how many people have tried to build scanning backs. The cheapest one seems to be $6,500. I think it can be done cheaper. That's coming from someone who spent thousands to build his own robotic pano head when he could have bought a gigapan for a few hundred
I've also built some crude DOF adapters for my video camera, so I figured I'd do the same thing. Have the view camera show the image on some sort of ground glass and then raster image using a macro lens on an X/Y thing.
If you can point me to any people/sites that have done, or are working in this area, I'd be interested. I'm also happy to answer any questions, of course.
My other somewhat related question, if you're not going to go the chemical route, why not just do stitching to get the same LF effect. For example I did this test of my daughter using 27 photos stitched together from DSLR shots.