An interesting find today at a local antique store. Judging by the groves on the backsides I’d say these were for use on a showcard press. I once found a solid plastic letter, but these are different. These are yellow plastic mounted on wood. 28-line height. I picked up the following letters; L, R, A, X, G, W, V, B, M, E. Manufacturer unknown. Anyone know anything about these?