This is likely a stupid idea but thought I'd ask. What's the worst that could happen? You all get a good laugh? -)) Anyways. I'd love a 6x12 roll film back. The problem is I doubt I could find one that I could justify the price. Throw in the odd comment about questionable film flatness for the cheaper holders. Now I have plenty of 4x5 holders. I have tape. I have 120 film. Lets say I tape some film to the inside of the holder. Any chance this could work?