I see someone beat me to it! If there's any questions for anyone who has interest in trying to work with this, I'd be more than happy to answer both here or on the mailing list.
Right now there's only one film back design, which is 6x6 but can be modified to 6x7. However, it shouldn't be too hard to create a 6x12 or 6x17 back based on the same design with a cone on the front.
I'm currently travelling for a bit and have no access to the right software, but once I get back I'll see if I can cook something up for that.