The design uses a lot of sheet metal and wood, as these were easy materials for me to work with (I no longer have milling machines and laser cutters at my disposal) and I had a bunch of material sitting around getting rusty. Luckily I had access to some sheet metal tools so it made it easy to work with the 18 gauge steel. You could achieve similar results with a band-saw and belt sander if you don't have access to a metal shear and brake.
My design uses a Schneider Super-Angulon 90mm F8 lens/shutter/aperture combo intended for 4x5 large-format cameras. This lens has a coverage of 216mm at the focal distance, so this will cover a 6x17 frame without issue. According to Schneider the flange focal distance of this lens is 98.8mm, this means that the lens must be held in parallel with the film and the distance from the surface of the film to the front face of the lens mount must be 98.8mm for optimal infinity focus. This number is a little bit flexible and I will admit that mine is not perfect. The image is slightly out of focus at f8, but the depth of field at f22 is high enough to make it a non-issue. My lens is probably pretty close to the hyperfocal distance of this lens, which is a good thing.
This camera opts for a simplified fixed-focus design, as I intend to use it for landscape and architecture photography only. At f22, the nearest object in focus will be about 10 feet away, which is perfectly fine for my purposes.
The film transport mechanism is just two knobs which turn a metal key that sticks into the top of a 120 film spool. The film is pulled from the supplying spool and rolled onto the receiving spool after each shot. Having two knobs makes it easier to roll because you can relieve the tension on the film by turning the supply spool and pull the film using the receiving spool. If you advance the film too far, you can always roll it backwards, too.
120 film uses a paper back which has numbers printed on it to tell the user what frame they are on. This camera uses the 6cm x 4.5cm markings but uses every fourth number only, starting with 2. Since the images are so wide the camera only gets 4 shots per roll, at markings 2, 6, 10, 14. I included extra windows to see the markings for 6cm x 6cm and 6cm x 9cm as well, in case I ever want to make a mask and use a smaller frame size in the camera. Many old 120 cameras had this feature built in.
Since the camera has a very wide angle view, I used a peephole from a door as a viewfinder. The finder is masked with some dark stickers to match the image frame.