I decided to do this on the beach to avoid hauling copious amounts of sand into a rented beach house (you are welcome homeowner). I will tell you, depending on the beach you are at, the sand will be different affecting how intricate you can be with your mold. The sand at the Outer Banks is pretty coarse and we could not letter or do small casts. Feet and hands worked the best for us. Try it and you will be able to tell if the sand will cooperate.
If you decide to do this at home, buy sand at any home improvement store. Be sure to get the finest grain they offer, you will get a much more detailed cast. While you are there, pick up a box of Plaster of Paris, they sell it there too.
These casts are pretty easy to break, so if you want to keep it FOREVER don't let your kids play with them.
What you need:
tray to hold sand (if you are doing this at home)
Plaster of Paris
bowl and spoon (metal) to mix plaster
items to make molds of (keep it simple, shells, hands, feet or simply designed items)
What you do:
Mix the sand with enough water to make it damp, but not wet.
Make impressions in the damp sand with items. (Please note, I am using shells in this picture but they did not turn out well, the sand was too coarse. We will do this project again at home using finer sand and shells.)
Mix up the plaster following directions. Mine was a 4-1 ratio of water to mix. Add more water if needed to make it pourable. Pour mix over molds. Let dry according to package directions. Mine were ready after an hour.
Gently brush off excess sand with a soft brush to reveal your cast!
***Want another cool kid friendly project? Check out how to make salt clay.***