This is a really big back to move, and it will require two coupled rack and pinions to keep the moving plate from binding. The back lid of the box is going to be about 24". I would prefer a brass rack and pinion, but I could find only one on ebay in a 500mm size length. Those sold by Edmunds are too expensive, so I settled for two 0.5 Mod 8mm x 8mm x 500mm steel racks
with matching .5Mod 16 teeth pinions with a 3mm hole.
I sketched the setup roughly in my notebook. The racks will be attached to the lid /base, and the shaft and pinions to a guided sliding cart to which the back of the camera will be attached.
We will need two substantial brass knurled focusing knobs to turn the two pinions mounted on the same shaft. We will also need similar smaller brass knobs to attach the front board and the back so we get tilts, and two larger ones for swings. Specialized Knobs are very hard to find is expensive, but I found a cheap alternative in drawer knobs on Amazon. I got a pair of 28mm brass knobs for a mere $8. The mounting screws are 4mm, so I will have to modify the pinions to accept a 4mm shaft.
a pair of T knobs to lock the front and back swings for $10:
and a 6 pack of 26mm brass knobs for $8 to lock the tilts:
I also ordered some real wide knobs from eBay for $15:
Here is the basic layout of the box:
Here is the layout of the focusing rack and pinions mechanism:
and a detail view:
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