The freearm models became more common after WWII, among the first were Elna and Bernina. I think Husqvarna had an early one too. Elna 1 is a portable all metal straight stitcher, and I guess you should be able to find an early freearm Pfaff with a bit of effort. If you find one, there's a good chance it's made by Bernina or Elna. It took Pfaff a few years to get their factory back after the war, and by the 1950s plastic was the new material and everybody seemed to jump for it with enthusiasm, like it was obligatory.
That said, there are probably a few all metal models out there. Pfaff 260 and 360 come in slightly different versions, but I think some of them are all metal, or mostly metal. They are sturdy machines, with extra amps to the motor. I don't know too much about the variations on them, but they are well worth taking a second look at. These are aluminium bodied machines. I have never seen a cast iron freearm model, I know one existed very early on, but the more moderns zigzaggers are far and few between until the 1950s.
Last edited by Mickey2; 08-27-2018 at 02:19 AM.