pinned and did...
diy side walk paint: 1 tablespoon of corn starch and 2 tablespoons of water , mix together and then add food coloring. It was that simple. I added a little more water to get the starch mixed up...it tended to clump up at the bottom. I would also recomend using a silcone contanier or one that you just throw away when finshed.
note: go easy on the food coloring ... a little goes a long way ... the darker the color the harder it was to wash off. seriously go easy on the color. I would also wash it off as soon as possible.
overall: A TOTAL HIT! Both kids loved this. They loved making it, mixing it, and painting with it. They even loved cleaning it up with the garden hose afterwards. This provided at least an hour of play time.