. . . like greetings or thank you cards that you don't want to throw away -----
stitch a signature in them and do something decorative with the ends of the threads. You may have to trim the cards down a little to fit the paper, or cut paper to fit. I was able to use half A4 by cutting the cards a bit.
Buttonhole stitch along the spine stitches. Blue and red threads to match the design.
The leftover threads were made into twisted cords and knotted, and the ends frayed into spiky tassels.