Rosenberg works out of a sun-filled studio at the street-facing end of the railroad apartment he shares with his boyfriend, Gil, who's a surfer, musician, and assistant to the color theorist Donald Kaufman. Although Rosenberg doesn’t fancy himself a musician, he’s the synth player in their band, Jacques Detergent. (“That's day-ter-GEANT,” he says with a French flourish.) When I visited, Rosenberg was working on their record cover — an early draft is pinned to the wall — and preparing for a solo exhibition in Oslo this month called "Wallhangings of Today."

“This is the main work,” he says with a laugh. “They may look unfinished, but they’re not.”

On his desk, Rosenberg keeps folders filled with unfinished pieces and paper he’s dying to use. “Definitely the first thing I do when I'm in a European city is go to the stationery or office-supply store. But most of it is found or from things you wouldn't necessarily buy for the paper — the inside of envelopes, packaging from a Bendel’s box, a yellowed page of a book. It’s not really the kind of thing you’d buy in a store.”

A 2008 piece called “Peak.” “The process for collage is just living with the stuff,” Rosenberg says. “Things come together on their own, which is always nice. You come into the studio one morning and two things are next to each other and they’re perfect. All you have to do is tape it. There’s a lot of adding and subtracting, but usually something tells me when a piece is done.”

His secondary material is removable tape. “Even the finished pieces are usually held together with it,” he says.

Rosenberg tends to find the backs of pieces, where he dates and signs them, as beautiful as the fronts. Though he concedes: “Most people don’t give a shit.”

He spends much of his time traveling — on surf trips to Hawaii or Costa Rica with Gil or on nature-inspired jaunts to Iceland and Norway, two of his favorite countries — and from each trip he returns with countless objects. Currently on display are rocks from Iceland, an old battery tester picked up from an Utrecht flea market, a notebook collection that holds his sketches and watercolors (top left), a Finnish grocery list, a French pocket flashlight, a framed collage, and on the bottom right, a stack of book covers by the Dutch artist Dick Bruna.

Bruna, who also often worked with paper cutouts, is one of Rosenberg’s biggest inspirations. “Before he started doing Miffy, his father had a paperback book company and Bruna designed all of the covers. They’re basically detective novels in Dutch, so I eventually started ripping the covers off of the books. I really didn’t need to have a huge shelf of books I can’t read.”

On the shelves behind his desk are small boxes filled with collections. “I’m never quite sure what’s in each one until I open it one day,” says Rosenberg. “One has random photos of cats on a farm, one has broken rubberbands, cat whiskers, pieces of lichen, pinecones, wooden houses, candy wrappers, on and on. It’s a good place to look for inspiration.”

Supplies are kept close at hand. Earlier this spring, Sight Unseen asked Rosenberg to design a mobile for our ICFF exhibition. Rosenberg began hunting for various pencils to hang from chicken wire and suddenly realized he had dozens. “Instant collection!” he says.

In the back are four of Rosenberg’s Swedish trolls. He also has a Finnish troll collection, but when I visited he’d just sent them to his parents’ house as they were beginning to take over the studio. The difference between Swedish and Finnish trolls? “Finnish trolls are made of natural materials, like reindeer fur and leather and dried mushrooms,” he says. “They’re such a normal part of life in Scandinavia.”

“This is just a weird game. I have no clue what it is, I just think it looks nice,” laughs Rosenberg.

A color-sample book found at a New York flea market, “or maybe in the garbage?” Rosenberg says. “I find a lot of things on the street.”

Rosenberg’s works are often geometric in form, but more and more his shapes are influenced by his love of nature. “I love going to European cities,” he says, “but now all I want to do is go into the mountains, or fishing or mushroom hunting. That’s what we do here — every weekend we go into the forest in New York or New Jersey.”

“I’m way into mushroom subculture,” he says. “The New York Mycalogical Society, which was actually founded by John Cage, has walks every weekend.”

A recent collage Rosenberg made using a Rudolf Steiner book he found on the street in Amsterdam. On its left panel is a recent experiment with paper line drawings. The rocks he picked up on the beach in Oahu in February.

Old matchbook labels from Europe, picked up on eBay.

“This is an instant collection I found at an amazing estate sale a few weeks ago, at a brownstone uptown,” Rosenberg says. “They were selling everything in the house, but the kid had been collecting all of these No Parking signs from around New York for years. The amazing thing about this is that he took all of the parking signs for all of the days, scanned them, and then made one that said No Parking Yesterday, which is so brilliant. This was with all of this stuff in the basement. He’d made all of these greeting cards, too. He was really into Xeroxing.”

Rosenberg's plastic-bag collection. “I could take it down but you’d be drowning in plastic bags,” he says. “The Plastic Bag Happenings at Kiosk and in Finland made the collection so much better.”

From the bags, Rosenberg has been sewing useful objects to sell at Kiosk. He often makes them submarine-shaped like this one to accommodate items like pencils and knitting needles. “I’m working on quilting the plastic to hold things like cameras.”

Rosenberg recently began collecting paper bags as well. “The plastic-bag collection includes things people have given me, but this is all me, which is really sad,” he laughs.

More paper ephemera. “When I travel, I collect every paper thing that could possibly pass through your hands,” Rosenberg says. “They all have beautiful textures to them. I keep them all and they somehow make their way into my work.”

A batik fabric from Senegal underneath a guidebook to sewing traditional African clothes. “Our godson James’s birthday was this past weekend so I made him a dashiki out of this,” Rosenberg says.

Rosenberg’s desk. At the bottom is a set of watercolors his mother, also an artist, bought for him. "I guess I grew up in a colorful house," Rosenberg says. "Didn't everyone?"

In the corner, a rare moment of calm. Of his often cluttered working space, he says, “I try to tone it down. I’ve tried to make my studio a serene place. I often think, wow, how nice for these artists whose studios have tables that are like empty. But it just doesn’t work for me. I need constant visual stimulation.”