Have made "sand" paintings using corn starch colored with dry powder
paint. Used cardboard for the base, sketched the design in pencil, then
added thin layer of glue (white) and sprinked (use spoon or tool) sand
over area. Let it dry a little then add next color. I did it with a
great number of students and their parents and had a very limited time.
Would emphasis design elements a lot before adding the sand.