Shell molding, also known as shell mold casting or the Croning process, is a form of metal casting. Shell mold casting allows the use of both ferrous and non-ferrous metals, most commonly using cast iron, carbon steel, alloy steel, stainless steel, aluminum alloys, and copper alloys. Typical parts are small-to-medium in size and require high accuracies, such as gear housings, cylinder heads, connecting rods, and lever arms.