This is an art activity I saw on the Artful Parent Blog. It looked so beautiful.
It is rubber cement, painted and sprinked over watercolor paper and left to dry. Later MD painted with watercolor on the paper. I had him do two, one with a painter's tape border that I later removed, and one without a border.
Ours did not turn out quite as beautiful as the Artful Parent's because of the dark colors and may have been a little nicer looking if I had done the rubber cement "designs" myself instead of letting MD do it by himself, but as with most things art, it was very much fun and I love to see his creations!