"Building my own camera was a really liberating process as a photographer. Sometimes you get into that rut of having big dreams of owning high-end camera gear. The reality is that if you use your imagination and a practical sense of what you want to accomplish, you can do most anything. I feel confident that I can pretty much make any camera I need (I'm currently up to 30x40" mounted on a garden wagon). I also just made one on the base of a wheelchair to hold a 125 lb aerial camera lens!
The wheelchair camera (my friends call it 'the sad robot') was just built last month. So far it is only an 8x10" camera, but it has a 600mm f/3.5 lens that projects an image about 16x20". I was told the lens came off a U2 spy plane -- it is a beast. I use a car jack to raise and lower the lens. I even needed to get a handicap ramp to get it into the van!"