Warbird Information Exchange

Does anyone know when the, now ubiquitous, engraved plastic placard was first introduced? Or when they became common in aircraft?


For clarification, I mean the ones with two layers of contrasting plastic - think desk nameplates

If you look in the Detail & Scale book on the F6F (it was on the coffee table) there seems to be some of them in the old, wartime era cockpit shots. They don't look exactly right, but pretty close.

Dan