Supplies needed: access to a chain link fence, finger paint, a large piece of paper, clothes pins, and a smock for child (an old shirt will do fine for this).
Attach the paper to the fence with paper clips.Let your child's masterpiece hang to dry while you hose them off and get them cleaned up. (Washable finger paint is wonderful!)
Idea found in a children's art book. Actual title of original source forgotten.