ST. LOUIS • Combine a glut of empty office space with a growing "freelance economy" and what do you get? Maybe you get a new way of thinking about what it means to go to the office.

That's the thinking behind St. Louis Coworking, a new home for freelancers, one-person shops and the self-employed that opened this week in the Shell Building downtown. It's the latest in a string of these sorts of collaborative workspaces — offering low overhead, month-to-month leases and an idea-bouncing vibe — to open in St. Louis in the past few years. And it's probably the highest-profile effort yet.

It is a fairly simple concept.

For $400 a month, you can rent a big U-shaped desk with phone and Internet, or split one for $300. For $100 a month, you can get a spot on one of the couches or tables scattered around. Wi-Fi, coffee and a business address come with the deal, but there is no long-term commitment, no utilities, none of the expenses that come with outfitting a full office.

The concept is designed to appeal to the growing number of people who are putting out their own shingles these days but often work from their basements or a nearby coffee shop, said Mike Tomko, chief technology officer at Scorch, a marketing firm that's spearheading the project.

"In this economy, there's a great need from people who need the amenities of an office but can't afford it," he said. "We're trying to fill that need."

Tomko, whose agency is located a few floors down in the Shell, has been studying co-working for a while. In the past few years, these spaces have popped up in cities such as Brooklyn, N.Y.; Cambridge, Mass.; and the Bay Area — housing tech startups and small creative firms. More recently, they have opened everywhere from Oklahoma City to Urbana, Ill.

When a major tenant left the Shell recently, Tomko, whose firm does marketing for the building, saw an opportunity. With downtown office vacancy north of 20 percent, filling the space with a traditional tenant could be tough.

"So this seemed like the best use of the space at the time," he said.

In just two weeks, the 10,000 square-foot 11th floor, with its brick walls, concrete pillars and exposed ductwork, was repurposed. Along the wall full of seven-foot windows looking out on downtown are dozens of desks, a conference room, a lounge, light tables for visual artists and tables and chairs.

The open floor plan and funky vibe, Tomko said, can help encourage interaction between the sorts of people who might not normally work together, say a real estate agent and a Web designer.

"You can walk across the room and ask someone a question," he said. "There's stuff you can pick up through osmosis. It's a good feeling."

It is also the kind of environment that can spark innovation, said Vince Volpe, who teaches entrepreneurship at St. Louis University.

Smart companies, he said, are increasingly designing their offices to encourage conversation and collegiality. Sure, people may talk around the water cooler about baseball, but they also share ideas about business. That interaction is hard to get when you work at home, or in a Starbucks.

"No matter how bright you are, you need to have your ideas tested by other people," he said. "And, for that, there's nothing quite like face-to-face conversation."

James Breaugh, a professor of management at the University of Missouri-St. Louis, noted that these setups can come with hidden costs, in this case parking and, perhaps, the city earnings tax. But he expects alternative work styles — be they independent contracting, telecommuting or self-employment — to keep getting more popular. An arrangement that eases the isolation of working alone, he said, has potential.

"I think a lot of this is just going to continue to expand," Breaugh said.

St. Louis Coworking is not the first of these sort of spaces in town.

For a while, Lisa Rokusek, a corporate recruiter, runs a small co-working space out of a home she owns in south St. Louis, though its use has ebbed and flowed, she said.

Last year, a California-based company called Cargo Bay turned a former Kmart in Hazelwood into low-cost storage and office space. Judy Notestine, a manager there, said the offices are mostly full, housing everyone from event planners to CPAs. They plan to open a second location next month in Ellisville.

Back downtown, things were starting to perk up in St. Louis Coworking's first few days. On Wednesday afternoon, a handful of people were trying it out, most equipped with little more than a laptop and a backpack. Like Danielle Little.

A freelance writer, Little usually works in a Borders or a coffee shop, even a McDonald's now that they have Wi-Fi. But on Wednesday she was trying out a desk. She liked it.

"This is actually a workspace," she said. "Other places, there's so much going on, and you get sidetracked."

Across the room sat Eric Castelli, a software developer who had been working out of his home in Columbia, Ill. He works alone but has twin 3-year-old girls at home. Getting out of the house gives him a chance to focus.

"I could have rented some office space, but then I'd need to set up Internet and a phone," he said. "Here I have everything I need."