That's a fascinating contraption. How thick is it? Do the stacking format frames come out? If so, what a clever idea. I have a holder with that one-sided design, but just for 8x10. There's a black metal spring that pushes the plate for tight, flat contact, like in yours, but I don't think it would work with the smaller formats. Very curious.
Has there ever been a thread comparing all the different designs of plate holders?
vintagepics: You might try Large Format Photography Forum if you don't have any luck buying a holder or two here.
If something like that fits a standard 8x10 film back, then that is what im looking for. I am using it for my calotype photography. I use the glass plates to help keep my paper nice and flat for exposure. Im actually shooting through the plate. I was looking for 8x10. I didn't know holders such as that came in variable sizes. Something like that would be even better.