It’s a little past 3 p.m. in Manhattan, and Jordan Seiler is getting ready for his next public-ad intervention. He uses a homemade key he forged earlier from scratch to access an ad display in a bus shelter. After rolling up the ad and tossing it, he installed a simple black-and-white pattern he designed in its place.

Seiler doesn’t consider the replacement poster art—more of an intervention. He calls his efforts the Public Ad Campaign.

His studio looks a lot like a warehouse. Every surface is stacked with heavy machinery. This is the lab where he welds the keys that give the public access to advertising displays in more than 40 cities around the world. “People have made them before,” Seiler says as he prepares to cut a metal rod for another key. “I think I’m just the first one to try and give them out to other people.” Whether you live in New York City, Shanghai, Amsterdam, or Istanbul, chances are Seiler can get you into local ad cases.

Sparks fly as he chomps away at various metal rods. I’m a little nervous with hot ash whizzing past my eyes. “The thing is, you can’t look directly at the spark or else it’ll burn your retina,” Seiler tells me, unhelpfully. He inserts a tiny screw into the end of the cut rod. “This ends up being the actual thing that grabs the locking mechanism,” he says. “It’s a nice little workaround for what is a nicely milled tool on their end. This is just a kind of ghetto version that works.”

Seiler’s work seeks to remind you that if you live in a major city, your eyes are currency. Agencies are constantly coming up with new ways to turn public spaces into ads. This is what the Public Ad Campaign hopes to fight. Seiler wants to distribute his keys as widely as possible to everyday people so they can help quiet the unavoidable ads into a dull roar.

Artists around the world have used his keys to install art along your daily commute. ELLE, TAEKS, the Flower Guy, Spectre, Lister, and more have all used Seiler’s keys to hijack the public spaces as a venue for their art. The hashtag #YeahWeGotKeysForThat keeps track of it all. But it isn’t only artists who are buying the keys; Jordan said he also sells keys to “people who just want to participate in the civil disobedience.” Seiler, along with collaborator Jowy Romano of the Subway Art Blog, also developed an iPhone app that uses augmented reality to swap subway ads with a curated selection of art to help turn your commute from a series of ads into a gallery exhibition.

Seiler said his project is intended to start a dialogue, not displace every ad in a given city. He sometimes stands close to his installations for hours after an “intervention” to survey the public. On the general reaction he gets, he says, laughing: “It’s hard to find anyone who actually likes ads.”