G3D furnaces are all delivered complete with a digital controller that has 9 individual programs. These digital controllers are available to purchase as a standalone unit, to retrofit to your existing furnace. All G3D furnaces are manufactured from stainless steel, and are specifically designed to give excellent performance for the jewelry casting process. G3D furnaces are all delivered complete with a digital controller that has 9 individual programs. These digital controllers are available to purchase as a standalone unit, to retrofit to your existing furnace. All G3D furnaces are manufactured from stainless steel, and are specifically designed to give excellent performance for the jewelry casting process.