While viewing chip manufacturers' videos, there was mentioned by one house that their plaques consisted of up to four layers of laminate. BG notes in some of their older catalogs from the 1980's, their plaques are fabricated with up to fifteen layers of laminate.

Though, I cannot locate any mention of a plaque with a square or rectangle lunette such as this 1940 plaque. It may be Caro.

Also, about in 1990, BG sent me some artwork of planned diamond, heart, club and spade-shaped lunettes, though I do not recall ever seeing any of those plaques, afterwards.