Hi Ross,
I am a member although I have not been active on the GMB for quite some time now.
I sent you two eBay links, and one link to my two FM birds with label.
This is FM Konstglas, Ronneby, Sweden.
By the way, I never said that I consider these ”somewhat rare”.
However, many objects in eBay listings are usually ”rare” or ”unique” but that is the words from many eBay sellers. Things are seldom rare.

The bird is a 1960’s model.
I have so far not come across any FM from the 1960’s that are signed so the absence of a signature tells us nothing.
We always have to look at the details. Large pictures, in focus, are always helpful, and a picture of the base/bottom is a must.
My two birds are made approx. 1961-1963.
Carlovision’s bird probably made mid/late 1960’s.
I'm including 3 pictures for you.
Ingela