Just for a little amusement on a Friday morning, and to point out that anything that allows you to make a mark can be a medium for visual expression, here’s an article from the Austin American-Statesman about Scott Wade, who draws reasonably complex images in the road dust that accumulates on the back of his Mini Cooper.
Wade uses his fingers, as you might expect, but also paintbrushes, to lightly smear or lift off the dust, and popsicle sticks, I assume for a “palette knife” effect.
Talk about temporary art.