Joe Hebenstreit is Frog Design's principal engineer and an amateur wedding ring designer. When it came time for Joe Hebenstreit to buy a wedding ring for his wife-to-be, he stuck with what he knew. That didn't involve going to the neighborhood jewelry store or venturing into a Tiffany's. Instead, Hebenstreit simply designed the ring in CAD by himself and then printed out a three-dimensional prototype using a 3-D printer.

"I designed it in 3-D, printed it out in wax, and then cast it in platinum at a high temperature casting place," Hebenstreit explains nonchalantly. "You can do a lot of cool things with 3-D printers," he continues. "They come up with new uses for them all the time."

Granted, as the principal engineer for Palo Alto-based industrial design shop Frog Design, Hebenstreit has access to gadgets that most geek grooms can only dream of. But 3-D printers aren't just handy for making wedding rings. Armed with new capabilities, they're taking a central role in the rapid prototyping and even production of consumer products.

The 3-D printer at Frog Design's Palo Alto headquarters measures approximately 10 x 10 x 12 inches. While this printer is relatively small, some can be as big as walk-in closets.

The technology behind 3-D printers isn't new. Rapid prototyping machines have existed in myriad forms since the early 1980s, but the pace at which new capabilities and printing materials are being added to the machines is astonishing, says Scott Summit, the co-founder of San Francisco-based industrial design firm Summit ID. These printers typically work by spewing out successive layers of a given material to build a three-dimensional object, slice by horizontal slice.

These end results aren't just prototypes or proof-of-concepts any more. As the technology has evolved, 3-D printers are now capable of printing out fully functional finished products. For example, according to Summit, battleships and aircraft carriers now make extensive use of selective laser sintering (SLS) printers, which can "print out" materials like titanium, cobalt chromium and polyamide, to fabricate spare parts on the spot instead of carrying huge warehouses full of replacements. And some manufacturers of 3-D printers even use their own products to create parts for the next generation of printers. "It's like the Terminator self-replicator machine or something," Summit says. "Machines are making the next-generation machines."

Designers and engineers can leave Frog Design's 3-D printer running over the weekend if need be to print out consecutive models, one on top of the other.

The printer at Frog Design, which is used for more traditional modeling purposes, uses two materials: ABS (acrylonitrile butadiene styrene) plastic and industrial-strength glue. The glue is what enables the machine to build hollow or concave objects without letting them collapse in on themselves.

These rapid prototyping printers are bringing an entirely very new mentality to design, where the user becomes a key participant in the creation of the product. Summit and Hebenstreit both cite hearing aids as one example of this new approach.

"They stick some clay in your ear, it takes the shape of your ear, then they 3-D laser scan that and it gets fabricated by a 3-D printer," Summit explains. "It's kind of co-designed by your ear – by your personal geometry."

This personalized approach to design can also be a godsend for new designers trying to break into the business. Teaming up with those who own and operate 3-D printers, designers open a web store with little more than a handful of designs. A customer simply chooses the design he or she wants, a rented printer fabricates the product, a traditional 2-D printer creates a mailing label, and Fed Ex picks up the box and ships it to the customer.

Hebenstreit shows off a small component model he was able to print out in a matter of minutes.

Companies like Freedom of Creation, which sells home furnishings, are already starting to experiment with this approach to doing business without relying on inventory or big capital investments.

"(3-D printers) are basically like the new car that landed in everybody's driveway," Summit concludes. "(Every designer) wants to try them out and see what they can do."

Birth of a Gadget: Inside the Industrial Design Process

At Last! PC Industry Gets Serious About Good Design

Gadget Lab: Desktop Factory: (Almost) Affordable 3-D Printer

3-D Printing's Great Leap Forward