adhesive foam sheets. You can just draw right on them with a ballpoint pen, and that leaves enough of a depression to make an instant stamp. Plus, the foam squishes in a really satisfying way as you draw. Quick, easy, inexpensive, endless possibility.
Make your own custom cookie stamps with salt dough!! I also wanted to pin this on "For the Littles" and "Eat It:Sweeties" but thought it was more Arty than anything. And I really want some shortbread now. :)