A start-up called Desktop Metal has developed 3-D printers that can produce metal objects safely, in smaller spaces and for a lower cost than traditional manufacturing, which requires expensive machinery, lots of floor space and risky physical labor. The company just closed a $115 million round of venture funding to deliver its first batch of machines to customers within the U.S., founder and CEO Ric Fulop said Monday. The series D investment brings Desktop Metal's total capital raised to $212 million. The deal values the company at more than $1 billion, sources familiar with the deal confirmed. Investors include venture firms such as NEA and Lux Capital betting on advanced technologies and corporations likely to use the start-up's printers in their own operations. Corporate backers include BMW, GE Ventures, GV (formerly known as Google Ventures), Lowe's and Techtronic Industries, which owns Hoover, Dirt Devil, Ryobi and other power tool and appliance brands.

"This team developed a product that solves a very technologically complex problem in about 18 months," said Dayna Grayson, a tech investor with NEA. "We re-upped our investment seeing their ability to execute, and because we believe there's a very large, addressable market here." Last year, the entire additive manufacturing industry produced $5.1 billion in revenue, with just about $1 billion attributed to metal 3-D printing, according to the Wohlers Report 2016. But additive manufacturing is expected to grow across the board, Grayson said, especially in aerospace and automotive. Desktop Metal's machines work by binding metal and ceramic powders into a soft polymer. They extrude layers of this mixture to make an object, which is then placed into a furnace for what the company calls "microwave-enhanced sintering." The polymer burns off there, and the metal fuses together without losing its shape. Ceramic layers keep metal parts from fusing wherever a designer wanted to separate pieces. The printed objects are ready to use out of the furnace, no retooling required, Fulop said. They are comparable to cast metal parts in terms of structural integrity, he said.