The photos below show a lensboard that was built to accept a flange with a diameter greater than the wide or height of the lens board, i.e., the flange "overhangs" the sides of the lensboard. The spacer was cut from a material call phenolic paper, which is inexpensive and works easily. However, the spacer could have been cut from 3/32" thick plywood or other materials. The edges of the spacer were colored with a black "Sharpie" permanent ink marker for appearance.


3/32" thick Phenolic Paper spacer on top of the lensboard and flange:


Phenolic Paper spacer between the flange and lensboard during the trial fit:


Completed lensboard with the lens attached in the camera:



Another shot of the subject lensboard on the right that shows how far past the lensboard the flange overhangs: