Thought I'd share this; the DIY methods to hold a film carrier I've seen have all been kind of clunky - I just copied the idea of how a view camera's rear standard works, a couple springs, screws and a piece of sanded wood. Works exactly like my "real" 4x5 cameras. Remember to add the light-trap groove and you're good! This was a prototype, I planned on redoing it with nicer wood, but it works fine so I just stuck with the plywood. (It's stubby as I wanted an extreme wide angle). The step-ring allows me to stick a lens cap on it when packed.