I agree with Gary. Here is a scan of the obverse of mine. All parts are magnetic.
The only "reference" on gorget that I know of is Dieter and Odegard's book "Gorgets of the Third Reich". You might try a book service as it is OOP. But still it only provides an identification and general description with photos of a variety of III Reich gorgets. I do not know of any reference discussing manufacturers and techniques.
