'Green' impellers made from stainless steel powder and adherent are alloyed with brass through a capillary process. Here the brass is poured into the crucible container before being heated to 1100 degrees Celcius. Manufacturers are increasingly using 3-D printers to make production parts, rather than just product prototypes. Based on a computer-aided design, the machines put down layer upon layer of a metal or plastic powder until a part or product is formed--kind of like a document prnter. ExOne in Irwin, Pa. makes the printers but is also a service provider that prints aerospace, automotive, energy and other parts for manufacturers.