Jessica Rosenkrantz’s business got its start when she was doing what many students do during their time off: trying to make a little money. But Jessica, an architecture student, wasn’t bussing tables or serving coffee; she was selling jewelry she crafted using a laser-cutter in the basement of Harvard University’s Graduate School of Design building.

"I had all these weird-looking laser-cutting scraps on my desk from a project I was working on, and people would come up to me and say, 'Hey, what’s that cool thing on your desk?'" the 30-year-old says. So she started a store on craft site Etsy.

That Etsy venture--which she started in 2007--turned into Nervous System, an eight-person "generative design studio" that Rosenkrantz runs with her boyfriend Jesse Louis-Rosenberg, 26, out of Somerville, MA. The "generative" part means that they design and sell 3-D printed jewelry, lamps, and housewares that draw inspiration from mathematical patterns taken from academia and nature. The company grossed $670,000 in revenue in 2012, a 116 percent increase from 2011. Markups are anywhere from 55 to 400 percent.

Nervous System is one of the forerunners in the consumer-side 3-D printed goods market that has sprung up over the last three years thanks to cost reductions in both consumer and industrial-level printers. It’s hard to disentangle the consumer-side numbers from the manufacturing-side ones, but the space as a whole generated $1.7 billion in revenues in 2012, according to a study by Global Industry Analysts.

Rosenkrantz attributes the consumer-side of the boom to the pop culture intrigue surrounding 3-D printing.

"It’s like a symbol of the times or something--one of those zeitgeist sort of things," she says. "People hear about how now machines can make anything and robots can construct complicated geometry that a human can never construct, and you see something in a store that was made that way that you can afford, and you go "oh, I want to buy that.'"

She and Louis-Rosenberg have credentials that are pretty unconventional for entrepreneurs in the 3-D-printed jewelry space. Before going on to Harvard for architecture, Rosenkrantz attended MIT where she received a degree in both architecture and biology and met Louis-Rosenberg, who was pursuing a degree in mathematics.

Leading up to the summer after the jewelry-selling experiment, she was debating between the typical, tedious internship that might lead into a career in architecture and letting the experiment run a little bit longer. She picked the latter.

"I was working on my portfolio for internships and I just realized one day that it was less satisfying than it had been designing new products and making things that people could actually use, and interact with, and purchase," Rosenkrantz said. She ran the Etsy store for the summer and decided to give architecture school one more chance in the fall. She ended up dropping out to pursue Nervous System full-time.

But what the duo learned in school is integral to the process behind designing their jewelry collections. Rosenkrantz and Louis-Rosenberg generate the patterns for their pieces--which resemble hollowed-out cellular structures--by borrowing and adapting algorithms and patterns from studies from academia. Rosenkratz’s initial interest, she says, was "in how patterns form in nature," and how that concept could transfer to art.

They then take their designs and have them 3-D printed offsite through Shapeways, a big name on the business-to-consumer side of the 3-D printing industry. After their goods have been sent back to their studio in Somerville, they’re processed and polished.

Nervous System purchased table space at some of the world’s largest design festivals--such as New York’s Design Week--in 2008 and 2009, showcasing their collections in New York, Japan, Sweden, and Australia. There, purchasers for the Museum of Modern Art and the Institute of Contemporary Art noticed the company's wares and thought the outlandish-looking jewelry would fit well in their gift shops. Today Nervous sells both through their website and via specialty stores and museum shops around the country.

Rosenkrantz says she believes that the future for her business, and the industry, is customizable jewelry sold online. She and Louis-Rosenberg have coded a Web application from scratch that lets customers design their own jewelry and housewares online--a typical piece costs between $60 and $125. She expects an influx of competitors to enter the space soon, riding on the wave of the 3-D printing craze, but she doesn’t expect her niche to get overcrowded because of the educational barriers.

The company also sells photochemically-etched and laser-cut pieces--a more traditional approach. But she says that most of the company's growth stems from demand for 3-D printed items.

"The demand for 3-D printed things is growing rapidly because it’s new. It’s something that people are just hearing about for the first time and want to see in real life and own an example of."