Mix together 2 parts sugar and 1 part hot water. You may want to add sugar or water as needed to get the right syrupy consistency. It should be thick enough to be used as fingerpaint. You will still be able to feel the grittiness of the sugar.
Line your table with paper. Give your toddler pieces of dark blue or black construction paper on which to paint. Offer some cotton balls to dip in the mixture and stick on the paper.
Let your toddler's creation dry flat. As it dries the sugar will turn white and sparkly. When it is totally dry, you can color over it with markers.