By Ronald Bailey

Leveraging 3D Printing technology to rapidly take an idea from concept to reality is exciting, even if all you're making is a generic-looking coffee mug. But it's another thing entirely to make an airplane with specialized powder that mimics conventional plastics. Knowing what materials can be used in 3D Printing—as well as what comparable materials can be used if the ideal one isn't available—is a new challenge for designers. Understanding how these materials can best be combined with design software and printing hardware is where the rubber meets the road—it's what saves costs in manufacturing, and what saves time in development and production runs, especially for manufacturers who only need small runs of a product or a finished part.

When the conventional production of a part or prototype calls for a specific material, 3D Printing companies likely offer at least one comparable material in terms of strength, durability, and flexibility. In other words, if you need a traditional wax, plastic, or metal, chances are that an equivalent, 3D-ready substance exists. (For more on materials that 3D Printing can't yet reproduce, click here.)

For example, 3D content-to-print solutions provider 3D Systems prints on-demand copies of an unmanned aerial vehicle frame for a customer using its DuraForm EX plastic powder, which is said to have the same toughness of conventional injection-molded ABS and polypropylene plastics. So instead of tooling up a conventional mold, injecting plastic resin into it, and then machining the rough edges off, that same customer can print a perfect copy of the frame, and then slot the motors and electronic parts into it immediately.

"We are selling a manufacturing solution, including software, printing machines, and materials," explains Steve Hanna, 3D Systems' global director of sales and marketing for rapid manufacturing materials.

It's a solution that saves the manufacturer the costs of designing, making the lathes, molds, and other machines necessary to manufacture the specific part—maintaining their materials' supply chain and assembly time.

A technique called Direct Metal Laser Sintering (DMLS) uses specially formulated metal powders—proprietary versions of materials typically used in manufacturing, e.g., stainless steel, nickel alloys, titanium—that are deposited by a printer one super-thin layer at a time, and then melted by a powerful internal laser to build up the finished prototype or product. This technology replaces the traditional manufacturing of production dies and molds that are currently produced by means of highly automated machine tools, and is already used to produce finished parts, such as custom-made medical and dental implants, and automotive parts.

By selling printers to manufacturers, 3D Systems and competitive printer firms such as Germany-based EOS and Israel-based Objet Ltd. are adopting a business model somewhat similar to the one pioneered by some standard printer manufacturing firms, which priced their inkjet printers attractively to support steady demand for proprietary inks. In comparable fashion, manufacturers that choose to purchase and operate 3D Printers in-house necessarily buy supplies of waxes, plastics, and metal powders that are formulated and optimized especially for those printers.

"Materials used in 3D Printing are generally more expensive compared to off-the-shelf commodity materials," says Hanna." [However] since articles made using 3D Printing avoid the expense and time-consuming investment in conventional tooling, in many cases the higher material costs may still result in lower unit costs and other benefits like faster time to market."

For an example of the cost of materials, we can look at Shapeways, a custom 3D Printing manufacturer and online marketplace. The lowest priced plastic that Shapeways offers is $1.40 per cubic centimeter, and stainless steel is $8.00 per cubic centimeter. (By the way, a cubic centimeter of stainless steel weighs 7.8 grams, which is just a bit more than a quarter of an ounce.)

The aftermarket for less expensive, printer-agnostic materials is still in its infancy. The DSM Functional Materials division of global science company Royal DSM N.V. already produces stereolithography printing materials that work in some of 3D Systems' machines, and there have been at least three unsuccessful attempts by smaller manufacturers to stake a claim in the off-brand printing material arena. (For more on stereolithography, see How 3D Printing Works.) Clearly, 3D Printing materials are more complex to make than printer ink, but it may not be long before these materials can be picked up in your local office supply store.

Ronald Bailey is the award-winning science correspondent for Reason magazine and Reason.com, where he writes a weekly science and technology column. He is the author of the book Liberation Biology: The Moral and Scientific Case for the Biotech Revolution (Prometheus, 2005), and his work was featured in The Best American Science and Nature Writing 2004. In 2006, Bailey was shortlisted by the editors of Nature Biotechnology as one of the personalities who have made the "most significant contributions" to biotechnology in the last 10 years.