I have about half of one of those in my basement. I picked it up at auction thinking I could make it into a camera, but never have. It's designed to work with a very specific shutter, I think, which goes in that mddile section with the blue stripes. The first stripe is marked with shutter speeds, the other with aperatures. I am not sure what size the hole is, but there is no place on mine for a lensboard. The auction looks like it includes a 3x4 Polaroid back, but mine does not include the part which connects to that, so I can't tell you about the interface.
Peter