In answer to a forum question about two-piece brass, this is a picture of some of my old brass (about 50 years old).  The top row are as-issued lapel insignias, stamped from thin sheet brass.  The middle piece on the left is a purchased two-piece version and across the bottom is a disassembled similar two-piece insignia.  Middle right is the purchased two-piece equivalent of the top right lapel insignia but it is Armor-specific rather than the generic issued brass.  The big piece in the middle is a two-piece hat insignia but I don't recall if it was issued that way or is another purchased piece.