- Homemade furnace for aluminum casting. Constructed from a 25-liter paint drum and a stainless steel bowl lid. Furnace lined with 50mm thick refractory material. Refractory cement made by mixing 1 part Portland cement, 1 part clay, and 7 parts of perlite. 280 mm diameter by 290 mm high. Weighs 15 kilograms. Handles 1 liter of molten aluminum.