Trade clothes at Swap-O-Rama- Rama in Venice

You’d be forgiven if you thought it was merely about looking cool. But “the key thing about swap is it’s a way to ‘upcycle,’ ” explains Lori Petitti, coordinator of Saturday’s used clothes marathon in Venice. “That’s the new buzz word, to take things that would otherwise be thrown away and end up in a landfill, to make them into things that you really want to keep.”

From informal bartering among friends to well-advertised all-comers bashes, clothing swaps have been flourishing in New York City and the Bay Area for about a decade. No wonder that in Los Angeles, where DIY culture intersects with a fashion epicenter and costume changes are almost as important in real life as onscreen, the notion has caught on.

Swap-O-Rama-Rama, a loose confederacy, was originally founded in New York by the performance artist and alternative lifestyle proponent Wendy Tremayne. The noncommercial franchise has spread to many American cities, as well as Vancouver and even Jerusalem. In late 2006, Tremayne’s brainchild made its first foray -- also organized by Petitti -- into Los Angeles, setting up shop at the Shrine Expo Center and attracting about 250 swappers.

Petitti signed on to the movement after getting a taste of Tremayne’s swap style at Make magazine’s Maker Faire, an eclectic annual national congregation of DIYers. A television producer with a crafty side gig at Hip Line Media, Petitti may be a de facto Angeleno, but she grew up in the Midwest where her mother taught her how to sew. “If you ask people in the [sewing] industry, they’ll tell you the business is coming back,” she says. “People are saying to me, ‘Wow, I never knew sewing could be so much fun.’ ”

At Swap-O-Rama-Rama, nine designers will be on hand to render services such as altering, stenciling and silk-screening, helping patrons customize their finds, fashion a grocery tote or transform old T-shirts into cuddly stuffed toys.

On the whole, though, what Petitti hopes Swap-O-Rama-Rama shoppers will pocket is a little tutorial in how-to-fish. “A lot of people don’t have practice being creative,” she says. With our glut of relatively inexpensive ready-made attire, “our society doesn’t require it.”

Be they havens for dyed-in-the-wool anti-consumerists, energetic do-it-yourselfers or high-end vintage glamour types, all swaps operate on the same symbiotic premise: One person’s back-of-the-closet atrocity is someone else’s find. Instead of simply divesting themselves of a bag of unwanted clothing, à la the Salvation Army, swappers get something in return -- but landfills don’t.

“The amount of textile waste in the U.S. is absurd,” Petitti says.