Go ahead -- wash your hands with these pastel ice cubes. They're actually soaps made using a plastic ice cube tray as a mold.
You'll also need blocks of glycerin, liquid food coloring, petroleum jelly, cotton swabs, and a microwavable container. Experiment with ice-cube trays of various shapes and sizes. Glycerin is usually sold in large blocks; to melt it, cut it to a size that will fit in a microwavable bowl or measuring cup. Smear a dab of liquid food coloring into the bowl or measuring cup with a cotton swab or coffee stirrer. Food coloring is very concentrated, so only use a dab; try mixing different colors.
Heat the glycerin in a microwave on high, stirring at 15-second intervals, until it's completely melted. Use a cotton swab to coat the inside of the ice-cube tray with petroleum jelly. Pour the melted glycerin into the tray, filling each section almost to the top. Cool for about 2 hours; the soap cubes will pop right out. Like cubes of ice, they'll also melt -- getting gradually smaller as each pair of hands is washed.