Size of Lensboard

I am looking for the exact measurements of a 6x6" Deardorff lensbord especially the corners. Is there a general thickness of the lensbords ?

The front of the board is 5 11/16" square, back of the board is 5 1/2"sq.
corners on the front are radiused to about 1/4", corners of back panel are square.
Thickness is appx 5/16" with the step from front to back being divided equally 5/32" ea.
One edge is tapered slightly appx 1/16" to allow for smooth fitment to the front standard.