Make several colors of salt dough. You can make them a few days before using them. Store them wrapped in plastic wrap and then in a zipper plastic bag inside the refrigerator. Before using them, make sure they are back to room temperature. If they are a bit dry, just add a bit of water and knead.
Use the salt dough as you would sculpt play dough. The great thing about it is that the salt dough sculptures will harden if you leave them out to dry at room temperature. Depending on the size of the pieces, it will take 2 to 7 days to dry completely. Turn the pieces from time to time for faster drying.