Everything you need to know about 3-D printing

What is 3-D printing?

It's a revolutionary manufacturing process in which the design for physical objects, from toys to jewelry to machine parts, can be digitally transmitted to a device that makes them out of plastic, metal, or ceramic materials. Once the stuff of science fiction, 3-D printers have rapidly evolved in recent years, becoming smaller, faster, and cheaper. A basic, microwave-size 3-D printer costs less than $1,000, making almost anyone a potential manufacturer. Tonight Show host Jay Leno uses a $30,000 device to print hard-to-find parts for his collection of classic cars. "It's a bit like when I was a kid and I watched The Jetsons and they'd walk up to a machine and press a button and get a steak dinner," Leno said. "But instead of a steak dinner, you're getting an old car part."

How do 3-D printers work?

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Just as a traditional ink-jet printer sprays ink onto a page line by line, modern 3-D devices deposit material onto a surface layer by layer, slowly building up a shape. The process begins with a designer using computer software to create a virtual 3-D model of an object, such as a toy car. Another program slices that model into thin horizontal sections and instructs the printer to lay down an exact replica of each slice. Some printers use a computer-controlled heated nozzle that moves back and forth across a print platform, setting down a layer of melted material. Others use a laser or electron beam to fuse powdered plastic or metal into the required shape. After each layer is completed, the printing platform is lowered by a fraction of a millimeter and the next layer is added, until the object is completed.

What's the advantage of this technology?

It makes it easier and cheaper for ordinary people to get into the business of making things. Inventors can print a model of their latest creation in a few hours, then tweak it and print again, instead of waiting weeks for a prototype to emerge from a factory. Injection molding, which requires toolmakers to build metal casts into which heated plastic is poured, is only cost-efficient for large-scale production. With 3-D printing, the cost per unit stays the same whether you manufacture one part or one million. "I can cost-effectively make a cellphone cover that is unique to every customer," said Ryan Wicker, an engineer at the University of Texas at El Paso. "I could build 100 different ones just as cost-effectively as building them all the same."

What are people printing now?

MyRobotNation.com lets customers design their own toy robot, which is manufactured on a 3-D printer, and the online retailer Shapeways.com sells everything from printed jewelry to desk toys. But the technology isn't being used just to build novelties. Danish firm Widex prints hearing aids perfectly tailored to the wearer's ear canal, and San Francisco's Bespoke Innovations is experimenting with printing custom-fitted prosthetic limbs. Aerospace firms like Boeing and EADS are starting to print complex aircraft parts in single pieces rather than multiple sections. By doing away with bolts and screws that previously held components together, 3-D printing has reduced the weight of certain parts by up to 30 percent, saving fuel costs, said Boeing design engineer Michael Hayes. Eventually, Boeing thinks it might be able to print an entire aircraft wing. "That's where the industry is trying to go," said Hayes.

What more could 3-D printing do?

A possible next step is for virtually every home to have its own printer. "Once that happens, it will change everything," said Carl Bass, CEO of Autodesk, which makes imaging software used by designers, architects, and engineers. "See something on Amazon you like? Instead of placing an order and waiting 24 hours for your FedEx package, just hit print and get it in minutes." Most experts, though, think the Jetsons era remains far off. The desktop 3-D printers available on the market now can only extrude plastic, limiting the objects they can produce. And even if you owned an advanced machine capable of creating whatever you wanted, you'd need a large stockpile of different materials. If your microwave breaks and you want to print a replacement part, "what are the chances that your 3-D printer is going to have the right material?" said industry analyst Terry Wohlers.

How might people use 3-D printers in the future?

Instead of fiddling around at home, we're likely to turn to manufacturing hubs with specialist 3-D printing machines, "rather like when people go to specialist shops to get higher quality photos printed," said Richard Hague, an expert on 3-D printing at Loughborough University in the U.K. Once introduced on an industrial scale, 3-D printing could have a profound economic impact. Companies would no longer need to keep huge warehouses filled with goods, as products could be printed locally on demand. And 3-D printing could compel American manufacturers to repatriate production now done abroad. "There is nothing to be gained by going overseas," said Bespoke Innovations co-founder Scott Summit, "except for higher shipping charges."

Download, print, aim, fire

Forget background checks and waiting periods. If you have a 3-D printer, you might soon be able to build a gun in your own home. That's the goal of a group called Defense Distributed, which wants to create downloadable blueprints anyone could use to print a fully functioning firearm. They're not there yet, but late last year the project's leader, University of Texas law student Cody Wilson, announced that the group had successfully fired six shots from a semiautomatic AR-15 rifle built with several printed plastic parts. The gun then fell apart. Rep. Steve Israel (D-N.Y.) is urging Congress to renew the Undetectable Firearms Act — which bans the production of guns that don't show up on metal detectors — before it expires at the end of 2013. "When the [act] was last renewed in 2003, a gun made by a 3-D printer was like a Star Trek episode," he said. "But now we know it's real."