Thank you for your comments.
As a result, I made two test lens boards, not recessed, but regular.
I am very happy with the results. My 150mm and 210mm Schneider are holding up beautifully and working on these boards. The boards bend a bit under load, so if you have lenses weighing more than 600 grams, I would recommend testing the board for bending under that load first. You may have to increase the thickness of the board and raise the clamp on the camera a bit.
A local 3D printing company made them for $6.50 each (that's translating to dollars).
I was quoted $15.5 a piece for 40mm reccessed board printing, but haven't ordered the print as I haven't bought a wide lens yet.
If it might be helpful to anyone, I attach the print files (.obj and .stl), I also attach the FreeCAD editable files, where you can easily tweak the details to fit your lenses.
https :// drive.google.com/drive/folders/1n6eK1SOd4Ga752gpjMIlxnXSkNG1U3M9?usp=sharing