Anybody else thought of this?
Affixing a stamp on a transparency cut-out (on the rougher side), and getting it postmarked directly there. The ink WILL be absorbed, because that rough side is not glossy.
Now I don't care anymore about the evolution of the gum on the back of that stamp, as it happens with a free-standing stamp.
I don't care if there are millions of copies in the print run of that stamp - mine could be unique in the world, as such.
I don't care about assigning it forever to only 1 postcard, as in traditional maximaphily.
I could temporarily superimpose it over anything I want - various postcards, images from calendars, magazines, books, to have fun experimenting in non-traditional maximaphily.
Then I can scan the variants I like.