Tin(?)-framed Small Postcards

Molly Marsh

My great-grandmother started my addiction to postcards when she bequeathed to me her small collection. Over 1,000 cards later, with a cutoff year of 1910, I am still buggered by 23 metal framed, 3" x 4" postcards. The paper part is also thicker than the regular postcards of that era. Most include a foldout easel on the back (as shown below) I can't seem to find any like them anywhere...nor any info about them. Obviously they are rare, indeed. Any internet links you may have to help me would be appreciated.
Sincerely, Molly Marsh
I've given you just a few examples to check out.

debbie galbraith

I also have never seen them -- there are photos that are about that size in frames (that I have forgot the name of ) but that is a new one on me- If you find what they are get back to the group and post them thanks for showing