It's not a new story, but the biggest and best architectural projects in Philadelphia always seem to end up in the hands of out-of-towners. The Barnes Foundation has a New York firm designing its new home. The Art Museum went to Los Angeles to snare Frank Gehry for its underground expansion. Even Drexel University chose a Minneapolis outfit to retrofit Market Street's iconic decorated shed, the ISI Building, one of Robert Venturi's important early works.

On top of that, well over 30 percent of Philadelphia's architects are out of work, thanks to the Great Recession, and the partners in some of the city's best-known firms openly fret that they don't know where their next job is coming from.

So, what's an ambitious young architect to do? Put on a show, of course.

An exhibit optimistically titled "Fertile Ground" opened yesterday at the Ice Box gallery on North American Street, and it is a free-for-all showcase featuring a dozen emerging Philadelphia firms, the majority of which are based in and around Northern Liberties.

Some participants have constructed elaborate installations for the show. Others treat it more as a marketing vehicle to highlight their recent work. While only a part had been installed when I visited, what I saw suggested that, despite a lousy real estate market and the city's famously conservative tastes, Philadelphia's architectural avant-garde is alive, well, and keeping busy.

The show's name alone says a lot. Because of the emergence of the international starchitect over the last two decades (beginning, perhaps, with Gehry's Guggenheim Museum in Bilbao, Spain) and the craze for branding buildings with recognizable logos, cities such as Philadelphia have gotten out of the habit of turning to their own design cadres to lead important commissions. Yet the architects in "Fertile Ground" clearly feel Philadelphia provides a different kind of sustenance.

At least three firms in the show - one of the many events organized under the DesignPhiladelphia rubric - already have made reputations by building edgy buildings in edgy neighborhoods: Erdy McHenry Architecture, Onion Flats, and Interface Studio Architects. Working (and often living) amid the decay of North Philadelphia, it's clear that these firms, and others in the show, have taken inspiration from the city's great tracts of vacant land and its wealth of hollowed-out factories.

Their designs embrace cheap, tough materials. They have little patience for the kind of precious detailing that is the stock-in-trade of firms that cater to high-end clients. Their work sometimes looks rough, even crude, but at its best it vibrates with energy and the can-do spirit of Philadelphia's manufacturing heyday. They are determined to recycle cities by making buildings that are deeply sustainable, and that don't merely collect points for the sake of a U.S. Green Building Council seal of approval.

Partly by necessity, the firms featured in the show gravitate to the kind of hard-luck projects where a tool belt is just as essential as a CAD software program. It's not unusual for these architects to pitch in with construction. At least two of the firms have followed the example of Onion Flats' Tim McDonald and become their own developer, rather than waiting for commissions to come in over the transom.

Becoming an architect/developer is a viable career path in Philadelphia because this is the land of cheap real estate. A North Philadelphia rowhouse lot can be picked up for almost nothing, allowing architects to work out new ideas, as Interface's Brian Phillips, the show's organizer, did with his recent $100K house. As Adam Montalbano of Moto Design Shop told me, young architects today can't count on a well-off parent to help jump-start a career, as Venturi did.

"Mother's House isn't happening," he observed, referring to Venturi's famous first project.

In conversations with these architects, one of the most common refrains you hear is the desire "to get back to the act of making things."

When I arrived at the Ice Box, in the Crane Arts Building, that's exactly what the architects were doing. DIGSAU's Jules Dingle was installing square facade panels, made from salvaged wood of different widths and origins, onto a small exhibit booth. They came from a job-training center his firm is designing in Wilmington, and they were beautiful in their texture, their color, and their sheer, hard-headed economy.

"This is a working-class town," he explained. "It's a town built on making things yourself, and that homegrown quality breeds creativity rather than conformity."

Immediately next to Dingle's spot, Jenny Sabine, a University of Pennsylvania professor and the leading theorist in the group, was taking a more speculative approach. She and two assistants were assembling a delicate, powder-white, computer-designed model based on the biological structure of a breast-cancer cell. While other firms in the show look to tough manufacturing lofts, she believes that studying something as unlikely as a cancer cell can teach architects about true structural resilience.

Across the vast room, Onion Flats' McDonald was taping together square cardboard boxes and arranging them Warhol-style to form a structure that is both a display case for, and a simulacrum of, his new line of low-cost, prefab housing modules, called Blox. Like a lot of emerging architects, he defines himself by what he is not: "This will be a critique of the Dwell magazine culture," he declared. "We find their emphasis on expensive, one-off, prefab structures absolutely ridiculous."

A show like this inevitably makes you want to ask: Is this the appearance of a new Philadelphia School?

The original arose in 1961 when Progressive Architecture magazine published an article declaring Philadelphia a hotbed of architectural rebellion and anointed Venturi, Louis Kahn, and Romaldo Giurgola as its ringleaders. Scholars, such as the Pratt Institute's John Lobell, have debated ever since whether any movement actually existed, and whether the three had anything in common.

What we know for sure is that their presence as practitioners and teachers made the city's architectural schools, especially Penn's, a mecca for aspiring architects from around the world. It's pretty clear from this show that the city is still living off the harvest.

"Fertile Ground" runs through Oct. 25 at the Ice Box, 1400 North American St. The opening reception will be 6 to 9 p.m. Tuesday. Admission is free. The Ice Box is open from noon to 6 p.m. Wednesdays through Sundays. Information: is-architects.com/fertileground.

Contact architecture critic Inga Saffron at 215-854-2213 or isaffron@phillynews.com.