Materials: gelatin powder, water, paper, and fingers :)
Mix a small amount of the powder with water to form a thin paste, about the consistency of white school glue. Using their fingers, help your child paint a picture with the Jello paint! Best part: the paint is edible. No worries about them licking their fingers between colors.
One note:
This activity can get messy, but it's easy to clean up with a warm washcloth. Just be careful that there aren't any fabrics nearby that you don't want tie-dyed.