Somehow a post I made last night disappeared early this morning - so here it is again.

Looking at the major support brasses on my tailboard cameras, the thickness of the brass is as follows:

18x24cm camera - 2.5mm

30x40cm camera - 3.25mm - but with additional thickness near the base rail (place for a slot which fits onto the rail) 4.5mm.

These are all flat brass pieces.