Plastic injection molding, metal casting and metal stamping are age-old processes that form the backbone of manufacturing. Traditionally, there's no better way to mass-produce plastic or metal parts.

PALO ALTO, CA—In the early 1970s, Hewlett-Packard created a stir when it launched the handheld calculator. Now, it hopes to do the same with industrial 3D printers

FINSPÅNG, Sweden—Siemens is investing $23.8 million to build a new factory here devoted to the mass production of 3D-printed metal components.