Mastro introduced five plastic guitar/ukulele models at New York's 1964 Toy Show, from the 30½" "Beatle-ist" down to the 5½" "Pin-Up" brooch. Made from Dow Chemical's resonating polystyrene "Styron," each carried band faces and facsimile autographs, shrink-wrapped with a pick and songbook. Selcol produced seven similar U.K. versions. As one Mastro craftsman put it: "We made so many ukuleles... we sold so many instruments."