I made these for a 6 for 6 swap on Alkymia, a European (only) group for ATC and spiritual art of all kinds.
The cards were cut twice the length of an ATC. First, I stamped and embossed the front of each ATC with a script stamp. The next step was to paint each card with gold and bronze acrylic. Then I punched out rectangles, affixed a scrap of metal mesh inside each card and folded it. The finishing touch was simply to weave various yarns through the mesh, leaving an inch or two hanging over at each side.
If I make more of these, I might try weaving the yarns into the mesh before closing and gluing the cards. I'm sure that would look nice, too.