From a 1956 Wilton's molds booklet, details on using candy molds to make fancy sugars for hot and cold beverages. This would be great for teas, wedding & bridal showers, and other fancy events. "Remember," it says, "you can make them in advance and keep them for weeks, ready to use whenever you have guests."
The recipe (from page 3):
Sugar Mix is easily prepared by mixing 3 teaspoons of slightly beaten egg white to two cups of sugar and adding color to suit.
Details of how to use the mix in the molds, including swift drying, are below.