A few years ago, Siegal was the It girl of prefabricated residential architecture, after newspapers and magazines (including Dwell) touted her use of recycled transoceanic shipping containers as the Next Big Thing. But windowless, uninsulated metal crates aren’t for everyone; they were more like the Honda Insight of the prefab world, conversation pieces that spurred ideas about how to make kit housing less expensive and more pragmatic. For Siegal, the answer, these days, is factory built: After years of hard work and heartbreak, she’s got her own prefab factory up and running in Chino, California, churning out custom houses and, lately, a school.

The nonprefab place where Siegal lays her head is a perpetual work in progress. About a mile from the beach, it’s been retrofitted with the sustainable materials and ideas she explores in her practice, from the single woodstove that heats the whole house to a new wide-open floor plan that welcomes sea breezes. It’s also an R&D zone: “I’m constantly doing stuff, like this door,” Siegal says, showing off a welded-steel- and-glass entry made by her longtime steel fabricator, whom she met during her premortgage days at SCI-Arc, the Southern California Institute of Architecture.

“But mostly, the things in here are either found objects or they were cheap,” Siegal notes. She points out a bookshelf she made from scrap lumber, and the huge glass doors that lead from the kitchen to the back garden; they originally came from a grocery store in East Los Angeles. A well-traveled Sub-Zero refrigerator rattles and hums in the kitchen, another dumpster-diving coup from a demolition site. The house’s bamboo flooring, from Smith & Fong in San Francisco, was free. “One of the things I do is I contact a company I want to work with, and say ‘Hey, I’ll promote you if you supply me with this thing for free, or give me a discount,’” she explains. It’s not as crass as it sounds; mooching is a time-honored tradition in the underfunded halls of academe, where Siegal spent most of her adult working life. “In my teaching, I would do the same thing,” she says with a laugh. “I’m really good at asking for things—and most people don’t ask.”

Jennifer’s father, Sidney Siegal, was a New York abstract painter who moved his family to rural Peterborough, New Hampshire, in the late 1960s. “Did you ever see that movie Pollock? That’s what my life was like,” she says, recalling expatriate urbanites cavorting at dinner parties in the woods. “I think that’s why I’m a risk taker. Growing up in a small town, you’re not fearful.” Portable retail runs in the family, too: After pushing a pirate hot dog cart in Boston after college, Siegal discovered that her grandfather once hawked dogs at Coney Island.

Siegal likes to call herself a “mobile entrepreneur,” and the theme pops up throughout her career—and in her backyard. Squatting amid the carefully clipped grass is a 200-square-foot wheeled truck trailer, deposited there by crane. Siegal bought it years ago for $1,500. She wanted to have a plan for it before moving it to her new house—but her mother thought otherwise. “She said, ‘Just get it into your backyard,’” Siegal laughs. “‘It doesn’t matter—if it’s there, you’ll figure it out.’”

The trailer is attached to Siegal’s renovated master bedroom, which includes a sunny new bath and laundry room. It’s technically a “bonus room,” a Los Angeles real-estate euphemism for the kind of unpermitted, ad-hoc addition that usually resembles something out of <i>The Silence of the Lambs</i>. But Siegal’s spin on it is a shiny, white aluminum-clad trailer with its original mahogany floors and tare-weight numbering intact, that she “just sort of glued to the house.”

“The reason I chose it is because it had openings on the back and on the side—it used to be a moving truck,” says Siegal of the almost dainty metal box. The first phase of customization entailed cutting holes for a window with a Sawzall, and swapping out the doors from steel to glass. “I still don’t really have a program for it,” she says of the funky, shed-like space. “Sometimes it’s yoga, sometimes it’s partying—but I just like it.”

Siegal notes that for the amount of money she’s sunk into the renovations, she could’ve demolished the house and started new. “When I bought it, you couldn’t even walk in—it was like a rat maze,” she recalls of the house she bought at a probate sale in 2002. But after all the changes, she says, “I feel like it’s me, like it’s my house.” Besides, recycling is the original shade of green. “It’s about sustainability,” Siegal explains. “You can start from scratch—or you can work with what you have.”

Siegal sits at her kitchen table and ponders her long-time love affair with architecture that “lives lightly upon the land.” “One of the reasons I was always fascinated with trailer parks is because they’re great communities— like the way the kibbutzim were started in Israel,” she says. “Everyone watches out for everyone else, they live in very small lots, it’s very efficient, and everyone tends to have a garden space.” Just outside her backyard trailer is a tiled hot tub, set amongst an amazing variety of succulents that Siegal has grown from clippings brought up from vacation trips to Baja California. “This is really what I actually love to do. More than anything,” Siegal says of her time spent in the garden.

She’s totally serious, too, especially in light of the path she’s taken from recycling queen to prefab factory boss, and lately, budding green-lifestyle maven. When she speaks about her mini-empire, Siegal sounds like a cross between Martha Stewart and the sun-creased hippie lady who sells sand candles down on the Venice Boardwalk. She just wants to make the world a better place—and to make a living. Her latest venture is a series of “urban green centers,” where city dwellers can buy everything from organic food to Jennifer Siegal–branded clothing, door handles, even entire houses. “My whole career has been completely intuitive,” says Siegal, staring at her sunny backyard. “It’s been an evolution. I can see now what the links are, but when I’m in the middle of it...” Her voice trails off as she realizes that what she’s doing now will someday be the middle of something else.

Jennifer Siegal’s other house is the portable ShowHouse, a 720-square-foot example of her factory-built prefab housing, wedged in among the boutiques and coffee bars on trendy Abbott Kinney Boulevard in Venice. “I set it up so people would have a place to come and kick the tires,” Siegal jokes. “What does modern prefab feel like?”

Siegel is a total nerd for new and earth-friendly building materials; among those on display in the ShowHouse are an iPort music system, with embedded speakers and a wall-mounted votive niche for an iPod; radiant heating panels—nicknamed “people heaters”—that efficiently warm you and your stuff, not the air around you; and Kirei board, a sustainable sorghum by-product that causes visitors to pet the walls and coo softly.

The 12-by-60-foot, steel-framed, slope-roofed ShowHouse is the fruit of Siegel’s collaboration with a formerly moribund industrial prefab factory, which for 30 years cranked out “nasty” construction trailers and depressing temporary classrooms. “Now they’re stoked,” Siegal says of their new focus on earth-friendly houses and schools. Siegel’s prefab sales pitch is concise: “I can do this in half the time and for a third of the cost of a conventional structure. Plus, it comes in on the back of a truck.”