table salt,several colors of chalk,ziploc baggies,jars (such as baby food jars)
Put salt in a baggie with a piece of colored chalk. Make sure the bag is closed. Rub the bag in your hands (or let the children do it) until all the salt is colored. Repeat with several different colors. Remove colored chalk from bags, and pour different amounts into the jars until full. Make sure the jars are completely full, or the colors will run together and ruin the effect. Once the jars are full, you can hot glue the lids on. Now you have a wonderfully inexpensive gift, or just a great paperweight to put on your desk!