It begins with a wax carving. These waxes will eventually form the negative spaces that will fill with molten metal. The wax is encased in a liquid plaster called investment that hardens quickly and can withstand very high temperatures. The wax and investment are contained in a steel cylinder called a flask. Wax can be engineered with different melting points for lost wax casting. In this photo, the purple wax has the highest melting temperature while the yellow wax has the lowest, so the yellow will "burn out" from the form first. Once all of the wax has evacuated from the investment in the kiln, the flask is placed where molten metal can be poured into the cavity where the wax once was. Centrifugal force or vacuum pressure is used to force the metal into every nook and cranny. The whole process takes anywhere from 6-24 hours.