Holy Crap! I have one sitting here I don't see pictured or mentioned. I will take pics of it in the next day or so. It's called the "Universal Sewing Machine Attachment That Makes Buttonholes" by London Specialties Co in Chicago Ill. Circa 1946
Personally, I think they could have shortened the name a bit.
They say it "sews on buttons, darns - mends, attach zippers, quilts, overcast seams" and fits any sewing machine.
It's the weirdest attachment I've seen yet for a sewing machine.
Contents of the box are:
2 elastic bands
2 pieces of twisted metal
2 sheets of instructions
a "small hoop"
I have a special place in my heart for these things too. Don't know why, but I seem to want to collect them too. I've got about a dozen of the things. Some are duplicates that may one day hit fleabay or bonanza.