There are disposable masks bought in bulk: light blue, three-ply, fastened with white elastic hoops. There are D.I.Y. masks, stitched at home, and designer masks, sold for $10 or $100.

Then there are masks made by a collective of the world’s most elite couturières: the seamstresses of Chanel, Dior and Saint Laurent, among others, who spent lockdown making more than 3,000 of them — a limited edition of sorts.

But these masks are not for sale, and the people wearing them are not influencers or celebrities. They are not the sort who, pre-pandemic, sat in the front row at Paris Fashion Week, wearing a mask plastered with bright white Chanel camellias. They are the city’s nurses, bakers and firefighters. And that distinction is important to the masks’ makers.

Their collective, called Tissuni (a portmanteau of the French words for “united fabric”), was founded in March by Marie Beatrice Boyer, a seamstress at Chanel.

This was early on in the pandemic, a few days before American designers like Christian Siriano began sewing masks from home. Ms. Boyer, 36, had heard from a midwife friend that a hospital in Grenoble was using fabric coverings to preserve its surgical masks.

She enlisted a few fellow Chanel seamstresses, and they began developing prototypes. On March 18, the day after Paris’s lockdown began, Ms. Boyer bought the Tissuni domain name.

Since then, the collective has grown to more than 100 members, according to Ms. Boyer. Many are haute couture seamstresses; in addition to Chanel, Dior and Saint Laurent, they come from Jean Paul Gaultier, Schiaparelli and the Paris Opera.

They made their masks from personal fabric supplies, and when those were depleted, used old curtains, pillowcases and clothes. They donated the masks to hospital workers, but also to law enforcement and Paris’s “front line”: cashiers, delivery people, taxi drivers.

Demand grew beyond the collective’s capabilities. “Sometimes we received more than 200 requests per day,” Ms. Boyer said.

The collective was adamant about not charging for the masks (though some recipients would offer payment as thanks). As the lockdown continued, Ms. Boyer watched as mask making shifted from a good, neighborly deed into a “commercial initiative.”

“What offends us is to see luxury brands selling fabric masks for more than $100, and to advertise them,” she said.

Her desire for more accessible couture was channeled into Tissuni’s next offering, in mid-May: an open-source design for a dress pattern. It was a summer dress, with a high neck, cap sleeves and drop waist, made with linen from northern France.

It was white, but Tissuni called it the “little green dress,” winking at the sustainability inherent in making one’s own clothes at home. It was an experiment in so-called slow fashion, a movement aiming to reduce waste.

More recently, though, Ms. Boyer has returned to work, focused on the next Chanel collection, which will be presented in a digital show on July 7.

In the weeks leading up to the couture shows, the petites mains of the Paris couture houses, like Ms. Boyer, can spend hundreds of hours of hunched-over labor on a single dress. They’re renowned for their skill in making intricate garments, tapping into what Ms. Boyer called “ancestral know-how, passed down from generation to generation of seamstresses.”

Yet making masks gave her an entirely new perspective on fashion.

“You realize that a simple piece of fabric, well cut, can have a direct impact on people’s lives,” she said. “We will never see a more beautiful collection than that of all the masks made and distributed free of charge by all the seamstresses and dressmakers from all houses and all regions.”