Interesting remnants of the paperloss seen on the backs. Whatever paper got stuch to the fronts came off fairly well leaving only traces and the ink.
That's not really hard to duplicate. Back in the 70's there was a brief "craft" fad for transparencies you could hang in the window. I did it with a couple then new commons and it was harder than other stuff only because the cardboard was thicker.
Put packing tape or a wide clear sticker over the printed or drawn item (Using a non water based ink if you're drawing it. ) Rub it down so there's no bubbles, then soak in water and once it's good and wet wipe away the paper leaving the ink stuck to the tape. Put a bit of a frame around it I used popsicle sticks-and hang in the window like a suncatcher.
They don't last. The adhesive on the tape gets gummy like it always does and attracts dust and eventually they're too ugly to keep.
Steve B