This past Sunday afternoon, the scene in downtown Oakland's hacker salon Tech Liminal resembled a friendly mad scientist's laboratory.

Presiding over a steaming metal mixing bowl, J.D. Zamfirescu stirred furiously as his lab partner, Kathryn Paisner, poured a steady stream of liquid nitrogen over the contents of the bowl. Around their plastic tarp-covered table, an all-ages group watched in giddy fascination as the liquid nitrogen - at -321 degrees Fahrenheit - overflowed the bowl and rushed across the table in thick clouds.

“Okay, who wants some ice cream?” Zamfirescu asked, beaming, as his audience passed along a box of plastic spoons.

With his wild mane of hair, Zamfirescu certainly looks the part of mad scientist. Along with his brother Gil, Zamfirescu is the creative mind behind Workshop Weekend, a series of two-day workshop extravaganzas, featuring topics ranging from coffee roasting to soldering to building a Geiger counter. Each Workshop Weekend is a collaborative community-based project - meaning that anyone can sign up to teach or attend workshops, which vary in length from one to three hours. Once a participant pays the $40 registration fee, he/she is free to sign up for an unlimited number of the weekend's available workshops – a model that encourages participants to take as many sessions as possible.

“We want people to be able to explore new ideas and topics without feeling like they have to commit to, like, a six-week class at a local community college,” Zamfirescu said. “People end up taking workshops that are maybe more on the fringe of their interests, but since they're already here, they get into it. We've had a lot of people who've gotten super excited about something that they thought was just a side interest.”

The Zamfirescu brothers both attended MIT - albeit four years apart - where they were inspired by the university's Splash program, in which undergrads and community members offer upwards of 400 different classes to middle- and high-schoolers over a single weekend each year. When Zamfirescu moved to the Bay Area five years ago, he started the Splash program at Stanford and has since helped to spread it to universities across the nation. But the brothers also wanted to establish the same model in a wider community, without having it limited only to students and youth.

The majority of Workshop Weekend's offerings are open to participants ages 13-101, because, hey, learning is a lifelong process. (Some classes, like Creating Lego Models, are open to ages 8 and up.)

The Zamfirescus established Workshop Weekend last year and so far have held four in 2012. Spanning both Saturday and Sunday, this past weekend's event took place out of four different venues in downtown Oakland, bringing a rush of activity to a stretch of Broadway that often stays quiet on weekends.

Zamfirescu said that Workshop Weekend manages to pay for itself, but ultimately the enterprise is entirely volunteer-run and is borne out of love of learning, not money. Moving forward, he said he'd like to hold the program in different cities throughout the Bay Area to accommodate the participants who come from as far away as San Jose to attend Oakland's workshops. Themed weekends – say, exclusively around crafting or 3D printing – are also a possibility.

“It's fun that it's open to all ages,” said Tom Fite, whose stop-motion filmmaking class included a wide swath of ages – including a 12-year-old who got to show off the R2-D2 shirt that he had made earlier that day in an iron-on graphics workshop. “It really lets everyone learn together.”

To learn more about Workshop Weekend, visit workshopweekend.net.