Printing 3D metal objects is a booming industry, with the market for products and services worth more than an estimated $2.3 billion in 2015—a nearly fivefold growth since 2010. For this type of manufacturing, a metal part is built up successively, layer by layer, over minutes or hours. Sometimes thousands of layers are added together to make a single piece, a reason why this process is conventionally referred to as “additive manufacturing” (AM).

Additive manufacturing machines are particularly handy for making objects with complex forms or geometry, or internal features like ducts or channels. They are becoming increasingly popular in the aerospace, automotive, medical, and technology industries to make complex pieces such as fuel injector nozzles for engines or titanium bone implants for skull, hip, and other repairs.

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