Like other manufacturers, Gottlieb first made mechanical pinball machines, including the first successful coin-operated pinball machine "Baffle Ball" in 1931. Electromechanical machines were produced starting in 1935. The 1947 development of player-actuated, solenoid-driven 2-inch bats called "flippers" revolutionized the industry. Players now had the ability to shoot the ball back up the playfield and get more points. The flippers first appeared on a Gottlieb game called "Humpty Dumpty", designed by Harry Mabs. By this time, the games also became noted for their artwork by Roy Parker.