I think this is going to go on a 6x12 camera (possibly with masks for 6x9). Probably fixed at hypoerfocal distance for f22 or with some simple focusing mount if I can think of a simple method.

I don't think it needs the accuracy of a rangefinder so a simple scale focus and a viewfinder (preferably optical) will do fine.

I have some pieces of 1/4" thick oak on my desk which would look good made into the shape of a camera!