Zeis made 1500 of these. The machines were were sold from 1941-1966. They were built during wartime, which may explain the lack of metal. Bill Jones is credited as having an earlier similar type machine.
From the Zeiss catalog… “All metal parts are rust proof. The housing of frame is made of bakelite. All parts are replaceable. Coils are hand wound with #24 magnet wire. Weight 9ox. Silver contact screw and spring have pure silver contacts.”
