Jerevan: I think you might be right, I was thinking 8x10 as my FKD is 18cmx24cm and an 8x10 frame is a little bit bigger for me! Point taken In fact, it might even be worth making a 4x5 frame and an 8x10 frame if there's demand enough to do so.

Trevor Crone: Cost is the biggest issue of course, and at the moment I don't know how much it'll be. I could use Pine rather than Oak to keep costs down, but I'd rather make something that isn't going to fall apart a year down the line! Although it doesn't have to be Oak, it's just what I have in my workshop at the moment!

Spring clips... I'd need to draw it really, but I envisage having a long spring clip running across the back which engages with a brass knob on either side. Screwing down the knob would apply the pressure to the back. To prevent the thread from being pulled out of the wood, I'd be using proper thread inserts designed for use in wood. The brass knobs would be machined specially to fit these units and the spring clip. Perhaps I really should make that drawing...