Hi Paul, I don't see it as being a Maico frame either. Definitely NOT.
But who knows it may handle better than the first Maico dual cradle frame(Maico X3 frame).
It has some similar design principles in frame componentry that Maico pursued, but she be no production Maico frame that I have ever seen in pictures or otherwise, I would be surprised if any of our members in Germany thinks otherwise too.
It takes alot of skill to produce a frame though, and the builder of that frame definitely had some skills, for sure.
But as we all know at the end of the day it boils down to design Geometrics.
The engine in those pics is a 250cc, first produced in 1963 as a side-port so it would fit into and clear the single down tube on the X2 frame.
Those same engine patterns were also used to develop the 360cc factory race engine in 1963.
I have German literature and magazines that tell the story of the first dual cradle frames on the race track in 1963
and then the new model advertised constantly from February 1964 as commercially available to the General public as the new X3 MC360.
The reason why the first Maico dual cradle frame was so wide in the down tubes was so it could accommodate that wide side port exhaust on those Alloy oval-barrel engines.
The first 360 alloy Maico oval barrel engine overpowered the single down tube X2 frame, hence the progression to a dual cradle frame,
first designed and built by a German race rider and friends (whose names I forget), not Maico.
Maybe what Doug has is that prototype frame, but I doubt it. And doubt that some how it would have made it to the states, it was secret squirrel German stuff.