Not unusual, laminating up thicker assemblies from 3, 5 or 7 ply thick 'plywood' sheet
material was not an uncommon technique in the period, or up to today for that matter.
Especially when dealing with curved surfaces. Looking at the photos on the blog
they are showing a laminated assembly of eleven layers of 5-ply, with the 5-ply made
of very thin veneers, and that 5-ply base material would be press-made. British
standard veneer thicknesses in the WWII period ranged from .01" - .05" in thickness,
so you could have one type of 5-ply that was .05" thick and another that was .25" thick.
'Twould depend on what was required. Note also that these plywoods were strictly veneer
sandwiches, not the mix of veneers and thicker cut filler material found in what most
people think of as plywood.
Anyhow most specialty plywood was then and is still today 'hand-made' in the sense that
the veneers are graded, picked, and laid in the sandwich by hand before the whole layer
cake is put in the press. More automated processes are used for standard costruction grade
stuff, however there is still a lot of hand work involved.
All this talk of plywood makes me think of a pet peeve ...
