I am thinking of making two cameras. One a pinhole. And one a modified pinhole that takes a holga lens and shutter on the front and takes 6cmx9cm plate holders. Thing is, I nee to figure out how to build a back. The front and sides are the easy part after all. But to get a working 4x5 back system in place is a bit trickier. Any help would be greatly apperciated. I figure a simple 4x5 pinhole owuld be my first attempt, with the Holgahole coming later.