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So, this exists: A working car has been 3D-printed out of carbon fiber plastic

(American Chemistry Council)

This is a car that is made almost entirely out of plastic. The Strati took 44 hours to make, and it's completely driveable. It's lighter and, if you believe its creators, also stronger than its metal counterparts. And it just might be the future of automotive technology everywhere.

Local Motors, the Phoenix-based 3D-printing company that built the car with help from Oak Ridge National Lab and the manufacturing company SABIC, says it's the first to 3D print both a body and chassis together. Other models, such as the Urbee, also use 3D-printed parts, but with a more traditionally manufactured frame.

Everything in the Strati that could be made as part of a single piece of plastic, was. This isn't your standard milk jug plastic, however. It's been mixed with carbon fibers for extra strength.

Although plastic might seem like an unusual choice for a car, the American Chemistry Council's Steve Russell says it's become an increasingly common component in vehicles. "Carbon fiber reinforced plastics are 50 percent lighter than steel, and 30 percent lighter than aluminum," says Russell, "but it has 12 times higher energy absorption."

That means big bonuses for safety and fuel efficiency, which has encouraged car manufacturers to make more and more of their vehicles out of the stuff. Today, carbon-fiber polymers may account for as much as 50 percent of a car's volume (while contributing to only 10 percent of its weight). It's also helped car makers to comply with rising federal emissions standards.

You might think of 3D printing as more of a hobbyist's activity. But there are some real engineering puzzles to be solved with the technology. Most 3D printers, as I've written before, are generally limited to printing in a single material. That makes it harder to make versatile use of them.

Then there's all the materials science that goes into it. Introducing the carbon fiber additive isn't as simple as dumping a load of powder into a vat of molten plastic.

"Part of the secret sauce is knowing how much of it to add, when [to add it], and getting the curing to spit out of the 3D jet at exactly the right time — that's really where the intellectual property resides," Russell says.

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