Soon she had taught herself to make masks and was donating them to fellow tenants of her apartment building, to a cleaning crew working in a Bronx public school and to homeless shelters, including one in East Williamsburg, Brooklyn, where there were masks for residents, but not staffers.

“The air of the staff completely changed when we were able to give them masks,” said Elizabeth Fasanya, the director of the shelter, operated by Project Renewal. “The color prints lift people’s moods.”

Samantha Casolari, an Italian-born photographer who lives in Williamsburg, found a different way to channel her artistry: an online sale of photographs to benefit embattled Elmhurst Hospital Center. The fund-raiser, Pictures for Elmhurst, raised nearly $1.4 million to buy ventilators, surgical masks, goggles and disposable scrubs.

Ms. Casolari and a small team, which included the photographer Jody Rogac, first asked photographers they knew to donate digital files so that prints could be made and sold for $150 each. After Pictures for Elmhurst gained momentum, they approached world-famous photographers, like Martin Parr and Rineke Dijkstra.

“Of course everyone said yes,” Ms. Rogac said.

Antwuan Sargent, an art critic and author of “The New Black Vanguard: Photography between Art and Fashion,” purchased prints by Tyler Mitchell, the first black artist to have a photograph on the cover of Vogue, and four others. He learned of the fund-raiser on Instagram. “I looked through and thought, I want that, I want that, I want that,” Mr. Sargent said.

The items that Lisa Kobs-Berrios and her husband, David Berrios, are selling in their own fund-raiser are not nearly as highbrow. But with backgrounds in marketing and luxury accessories, the couple has been able to raise thousands for hungry children.

Mrs. Kobs-Berrios and Mr. Berrios were hit with inspiration while taking their toddler, Rio, on walks through Morningside Heights in Manhattan. They often stop to watch fire trucks, which he adores. His parents noticed the signs on the rear of the trucks that said, “Keep back 200 feet.”