You have to do this. As Rainbow plays with her homemade Moonsand she shrieks and squeals "This is so much fun." I will show you this picture first as a warning. It's messy. Very messy. But it's a dry mess. In fact DON'T wipe it up - it will make a river of food colour. Just sweep it up or even better get your little one to sweep it up. There are many recipes out there all the same ration of sand, water and cornflour. We used our sandpit sand so sieved it with the cornflour first. Then mixed in the water mixed with food colouring. Go easy here. The texture you want is dry sand that when you squeeze it stays in a ball. If it is too liquid it won't hold it's shape and won't come out of the molds.
It's quite different to play with then playdough. Because of it's dry texture you can't roll it. Rainbow uses as selection of kitchen pieces - measuring cups and spoons, little bowls... You can also use cookie cutters if you place them on the table, fill with sand and press down on the sand. You also have to pack it quite firmly into a mold, much more so than damp beach sand.
Then when you're done, you crumble it back into the container. Then next time sprinkle on a little water and off you go again.
Reviews I've read on-line say it doesn't behave identically to the commercial moonsand but we had fun and it used ingredients that we have on hand.