RE: Exposure Control Holga
Regarding focus, at this point you might consider taking the shutter (with the Holga lens) off and putting it on an old folder. That is assuming that it's the lens aberrations that you love about the Holga and not the light leaks :)
8 x 20 Panoramic Picture Camera
Here is a camera that I built a couple of years ago. It took me about a year and a half to build in my spare time. I built the film holder first, then built the camera around the film holder. The hardest part seemed to be making the bellows. I am now designing a 14" x 17" camera. It will have its own built in rear extension. It will be similar to the Korona Pictorial View camera. I have 2 film holders that I purchased on Ebay, and will be building the camera around them.