The Brazilian couple Gisela and Gustavo Assis tend to do things the hard way—but then, nothing really worth having comes easily. Take Lapima, their three-year-old sunglasses line, which is already regarded by its rarified fan base as the “new old Celine” of eyewear. Made from translucent acetate and carved with a slight slope to flatter the face, the elegant frames were deemed a technical and financial impossibility by every manufacturer that the couple approached with their sketches. “They would tell us, ‘We don’t do jewelry,’ ” says Gustavo, 37, who designs the glasses. (“I’m the fit model,” notes Gisela, 40, with a laugh.) So the pair decided to take matters into their own hands. They bought eyewear-making machines from the 1960s, hired an expert engineer, and opened a factory in their hometown of Campinas, an hour and a half northwest of São Paulo. All this was happening while they were having their third child (Carlota, after whom their best-selling model is now named) and overseeing the gut renovation of their new house—another exquisitely complicated project.

“We’ve realized that if we become obsessed with an idea because of its beauty, we find a way to make it happen,” Gisela says.

Luiz Zerbini’s Máscara Caryota, 2016, hangs above vintage butterfly chairs in the living room.

Photograph by Fran Parente; Styled by Giovana Refatti.

Indeed, an appreciation for visual mastery has been the through line of their life together, which extends back to when they were children. Though Gisela and Gustavo officially met 16 years ago through her younger brother, they had actually crossed paths at a childhood companion’s birthday party when she was 6 and Gustavo was 2—there are snapshots that mutual friends showed them years later to prove it. Growing up in Campinas, Gisela planned on becoming a classical ballet dancer and trained for years in Europe, until an ankle injury sidelined her at age 25. Gustavo, meanwhile, drew constantly, hoping to become an architect, but at the urging of his family he ended up studying business administration. He went on to own franchises of the Brazilian fashion brands New Order and Osklen for 11 years, then, in 2013, sold them so that he and Gisela could focus on something creative that better reflected their passions and lifestyle.

Carlota, Joaquim, and Gustavo Assis (from left).

Photograph by Fran Parente; Styled by Giovana Refatti.

Clothing was out of the question. “We were tired of it,” explains Gustavo. “And fashion is too fast.” Sunglasses, however, appealed to them as design objects. After studying the market, they realized that there was a dearth of high-end eyewear made in Brazil—the country’s once-thriving optical industry deteriorated when companies moved their manufacturing to China in the 1990s. “Everyone began doing cheap glasses to compete,” says Gustavo. “We chose the opposite way.”

The couple import acetate from Italy, lenses from France, and hinges, which flex just the right amount, from Germany. “When we found out that the process was going to be expensive anyway, we went to the best suppliers,” says Gisela. Lapima is currently sold at Barneys New York, Moda Operandi, the Line, and the Webster, and Gisela and Gustavo plan to open their own U.S. shop later this year. Among the brand’s 18 styles are Milly Bold Edge, a chunky aviator that comes in tropical green, and Lisa, an oversize square number in ocean blue. As with the rest of the collection, they are inspired by organic shapes. “I’ve always been crazy about lines,” says Gustavo. “I like movement, motion. And color, which I think is a Brazilian thing. It reflects our happiness.”

A view of the backyard and swimming pool with Carlos Motta lounge chairs.

Photograph by Fran Parente; Styled by Giovana Refatti.

When he’s not creating eyewear, Gustavo is busy with other design projects, like the family’s inviting house, situated next to an old farm. Together with the young firm Way Architecture Yell—its founders, the Norman Foster protégés Priscilla Pinotti and Carlo Costa, are also a couple—they worked on the renovation, using mainly granite and Brazilian teak. “We wanted materials that made us feel like we were at the beach,” says Gustavo, who drives two hours to the closest surf spot whenever he can. Sliding doors allow sunlight to flood the rooms—and their sons, Gustavo, 11, and Joaquim, 9, to skateboard between the living room and terrace. “Campinas is not a city where people go out—there isn’t much to do. So we spend a lot of time at home with family and friends,” explains Gisela. “We wanted space.”

The floating staircase epitomizes the Assises’ commitment to design.

Photograph by Fran Parente; Styled by Giovana Refatti.

They decorated the interior sparingly, with furniture from Brazilian designers—minimalist tables by Jader Almeida, a pair of Sergio Rodrigues leather-slung Kilin chairs, and an oversize standing lamp by Alfio Lisi—as well as a suspended wood sideboard that Gustavo himself designed. Photographs by the German artist Janaina Tschäpe and by the Cuban collective Los Carpinteros, found on weekend trips to São Paulo galleries, hang on the walls. A set of floating stairs lead up to the roof for the ultimate viewing experience. “We go at night to see the moon and stars,” says Gustavo. But as far as he’s concerned, the pièce de résistance is the pool, which he designed so that the water line appears at the exact same level as the ground. People told him it wasn’t possible. “It was hard,” he says. “But we did it.”

A view of the dining room with Vik Muniz’s WWW (World Map), Pictures of Junk, 2008, and Janaina Tschäpe’s Candy, 2015 (from left).

Photograph by Fran Parente; Styled by Giovana Refatti. Hair by Carolina Aguilera; Makeup by Vanessa Rozan; Gisela Assis wears her own shoes; Gustavo Assis wears his own clothing; Pool, Staircase, Dining Room: Tiago Navas.