Sonoma Cast Stone molds its MetalCrete sinks from recycled concrete and plates them with copper, nickel, brass, bronze, or steel, resulting in a unit that's lighter than solid metal but without the ringing sound of hollow cast sinks, according to the manufacturer. The sinks are available in a variety of finishes, and the powder-coated steel or hardwood sink stands come with a natural or distressed finish. Sonoma Cast Stone. 877.939.9929.