Richard Smith needed to build a wall-climbing robot for a customer -- so he printed one.

Smith, director of Smith Engineering Gb Ltd., used a CAD program to design a 3D model of the WallRover, a dual-track roving robot with a spinning rotor in the chassis that creates enough suction to hold the device to a wall. He then sent the design file for each component to a 3D printer, which sliced the objects into sections less than 1/100th of an inch thick by printing it, one layer at a time, using molten ABS plastic as the "ink."

As a 3D printer begins fabricating an object, each layer gets fused or glued to the previous one and the product gradually gets built up. Under the hood, 3D printers use a variety of different fabrication techniques, several of which are based on ink-jet technology, and can use many different types of "build" materials to print three-dimensional objects. (To learn more about the different types of 3D printers, check out our comparison chart.)

Before buying a 3D printer, Smith would send its designs to a service bureau for fabrication, and parts took three or four days to turn around. Had Smith used a service bureau for the WallRover project -- which went through 22 design iterations -- it would have taken six months to complete, Smith says.

Instead, Smith was able to get a final design and fully functional prototype to the client within two weeks.

And he did it using a consumer-grade 3D "plastic jet printer" that he built from a kit. The RapMan, from 3D Systems' Bits From Bytes division, cost just $1,500. Smith spent another $180 for plastic filament -- the "ink" consumed by the printer. "It saved five months of development time and somewhere in the neighborhood of $15,000 to $20,000 in models" that were created in-house instead of being sent to a service bureau, he says.

Smaller and cheaper

3D printing isn't new. The manufacturing technique known today as 3D printing, also called additive manufacturing or direct digital manufacturing, has been used for rapid prototyping for decades. But over the last 24 months, prices have dropped to a level that makes it appealing to a wider audience.

The technology is more compact, particularly in the plastic jet-printing category. Cathy Lewis, vice president of global marketing at printer manufacturer 3D Systems Inc., says today's models are "ideal" for personal use.

3D design gets easier

It's relatively easy to use a free tool such as Google SketchUp to create simple objects for 3D printing. But for complex shapes and geometries, designers still reach for professional modeling tools like SolidWorks.

"Visualization software such as Google's SketchUp provides a fast entry route" to 3D computer-aided design (CAD), says Nick Grace, manager of RapidformRCA, which acts as a 3D printing service bureau for students at the Royal College of Art in London and uses many different software design tools and 3D printer technologies.

But, he adds, "the shortcuts made by these tools are not allowed for in the 3D printer's slicing routine." For example, some software may not fully render elements of an object that aren't needed from a particular viewpoint. That causes problems when the file is sent to the 3D printer. "We still regularly get unbuildable surface files or haphazardly constructed and translated data from files that render a perfectly coherent image," he says. In other words, they look fine on screen but won't print correctly.

Professional solid modeling tools do better job, but usually require specialized training and expertise. "The products today are pretty difficult to use," admits Gonzalo Martinez, director of strategic research at Autodesk.

CAD software makers are addressing the 3D content creation challenge in three ways: By introducing easier-to-use solid modeling tools for 3D content creation, by offering libraries of 3D objects that give users a head start on a design and by using specialized software such as Autodesk's 123D Photofly. This tool can combine a series of photographs of an object, taken from all sides, into a usable 3D model -- a process known as photogrammetry.

Professional tool developers are working "to make complex operations more simple," says Martinez. "Things that require training today you will be able to do with little training to create complex geometries."

For example, Autodesk 123D, a free tool for CAD novices, is a much-simplified version of the vendor's professional tools.

Other products, such as Rhino, a $995 program from McNeel, are edging closer to that middle ground between complexity and capability. "It is a high-end surface/mesh modeler, but has accessible controls and an excellent context-sensitive help with video clips," says Grace.

"We are still some way off the point when a novice can draw, model and print without help from a specialist," Grace says, "But that day will come."

But creating a printable 3D object can be tricky. Designs created in a CAD program need to be "water tight," or complete. "All surfaces have to be closed and lie on top of each other or you get holes in your part," says Jon Cobb, vice president of marketing at 3D printer vendor Stratasys.

The design then needs to be exported to a standard file format 3D printers can use, most often the stereolithography (STL) format, originally developed by 3D Systems, that has become a de-facto industry standard.

Until recently, the quality of STL files produced by CAD programs wasn't sufficient for 3D printing and required additional cleanup. But, Cobb says, that problem has largely gone away in professional solid modeling tools such as AutoCAD or SolidWorks. (Consumer-oriented design tools are a different story; see sidebar at left.)

Even so, Pete Basiliere, an analyst at Gartner who covers 3D printing, doesn't see consumers using the technology for personal printing of unique, one-off household items. "What's inhibiting consumer use is cost. It's too expensive for most people." Instead, he says, service bureaus may step in to fill those needs.

Another issue is that some objects need to have supports added so they don't collapse or sag before the materials fully harden. If an object needs to be supported during the printing process, the pre-processing driver software that comes with the 3D printer makes that determination and automatically adds any needed structural supports to the design.

The support material is usually different from the build material, and must be removed during a post-processing step that typically involves blowing off, breaking off, dissolving, melting or cutting away the unwanted material.

Price is right

Declining prices, improved quality and easier to use software are opening up demand for 3D printers. Commercial models -- capable of cranking out industrial manufacturing prototypes -- that once cost $100,000 now start at about $15,000, while personal 3D printers for the hobbyist and education market sell for less than $1,500.

"It used to be a six- or seven-figure cost," says Gartner's Basiliere.

Among industrial offerings, higher-end models add features such as the ability to print colors (although most can only print one color at a time), to run jobs faster, to print thinner layers for finer detail and to offer a larger printable area for creating larger objects.

For industrial designers doing prototyping, even an entry-level 3D printer is faster than going to a service bureau, and operating costs can come in as low as one-tenth of service bureau rates. The prices of 3D printers are now low enough to justify in departmental budgets, says Gartner's Basiliere.

Manufacturers, such as automakers, have traditionally used 3D printers in a lab or as part of a separate internal "service bureau," says Terry Wohlers, principal consultant and president of Wohlers Associates Inc., which tracks the 3D printing market. Now they are showing up in corporate offices, where they sit on the network like any other networked printer. "Because they're more affordable, now they're spread all across General Motors and Chrysler," he says.

Other industries use the technology, too. Ben White uses a 3D printer from Z Corp. to produce prototypes of window curtain poles, tracks, blinds and other hardware for Integra Products Ltd. "It's more economical to lease a printer than it is to keep sending products out for fabrication," says White, senior product design engineer. "We're at 10 to 15% of the cost of the service bureau," he says, the turnaround is faster and the models are more accurately rendered to the original design specifications. After six months the company is using the printer to produce 95% of its prototypes.

Others report similar savings. By using an HP DesignJet for rapid prototyping, Tintometer Ltd. sped up its product development times by 40% to 60%, says industrial designer Amy Penn. And the company, which manufactures industrial instruments that measure color, also uses the 3D printer to build finished products.

The DesignJet builds testing jigs that calibrate components before they're inserted into the final instrument during the manufacturing process. The parts more precisely meet the original specifications compared to what Tintometer was able to get from a service bureau, and are just as sturdy and a lot cheaper, says Penn. The 3D printer also made it cost effective to print concept parts that sales people can show to customers. "The ROI was about six months," she says.

Penn did not disclose what she paid, but she has the DesignJet 3D color unit, which sells for 16,200 Euros, or about $21,000 U.S. The monochrome version of the DesignJet 3D printer sells for 12,500 Euros.

In terms of shipments, the market for 3D printers remains relatively small. Unit shipments for professional use grew at a compound annual rate of 37% in 2010, according to Wohlers. This includes usage by industrial engineers, architects, engineers in traditional markets such as aerospace, consumer products, electronics, tool makers and other manufacturing concerns. But that 2010 growth amounted to just 6,164 units -- a tiny fraction of the 2D printer market. In 2010 there were over 44 million traditional printers shipped worldwide, according to IDC.

With only 51,000 3D printers sold worldwide since 1988 and 2.7 million solid modeling CAD seats worldwide, Wohlers estimates that there's plenty of room for growth. By 2015, Wohlers expects, shipments of industrial 3D printers will more than double to 15,000 units.

The potential for growth is one reason why Hewlett Packard dipped a toe in the water with the introduction of the DesignJet 3D, which HP sells only in Europe. The printer is a re-branded version of market leader Stratasys' uPrint 3D printer.

Objects made easy

Although they lack the capabilities of professional solid-modeling tools, all of the tools below can generate printable 3D objects -- and they're free.

Google SketchUp

Autodesk 123D

TinkerCAD

3DTin

Hobbyist Market

A growing hobbyist market has also developed for 3D printers; people use the technology to make everything from toys to drawer pulls. Free 3D modeling tools for hobbyists (see sidebar at right) make the creation process easier, while companies such as MakerBot Industries, LLC provide low-cost plastic extrusion, or plastic jet printers.

Manufacturers also offer libraries of preconfigured objects that users can work with. For example, MakerBot offers Thingiverse, a website where users can share objects they've created. Autodesk 123D offers a similar community.

Many personal 3D printers go to educational institutions, rather than homes. "We want to get these into the hands of kids," says MakerBot CEO Bre Pettis. "It gives them access to the raw power of innovation."

Unfortunately, simple 3D design software for home hobbyists isn't suitable for professional use, and professional tools are still quite complicated to use. That leaves a big gap between consumers and industrial designers. "Today you need to be an expert CAD user to create digital content, or you need a fancy scanner to capture 3D geometry of an object you want to print," says Lewis at 3D Systems.

The MakerBot 3D printer, which sells for $1,500, makes 3D objects by applying successive layers of molten ABS plastic. While designed for the home/hobby market, professional designers are finding the devices usable for some commercial applications. For example, Smith Engineering used a similar product to build and assemble the parts for a commercial robot prototype.

In 2010, 3D printer vendors shipped 5,978 personal 3D printers -- almost as many as sold into the professional market. But Wohlers doubts that a broad do-it-yourself at-home market will develop for personal 3D printers.