Hospital supply closets are starting to look like picked-over aisles at a grocery store.

Instead of empty shelves where the toilet paper and soup should be, hospitals are running low on the basic safety equipment they need to keep their doctors, nurses and patients safe.

But across Minnesota, volunteers are at work, filling the gaps in the medical supply chain with little more than 3-D printers and goodwill.

Working around the clock from their own homes, they've built thousands of protective face shields to give away to any hospital, hospice, nursing home, clinic or health care worker who needs one.

"We're close to 90 volunteers, [working] 24 hours a day," said Tyler Cooper, co-owner of Nordeast Makers, a co-working space in northeast Minneapolis for people who don't let a pandemic stop them from making themselves useful.

Nordeast Makers is "like a gym for makers," Cooper said. Instead of paying dues to get access to treadmills and weight machines, members get access to high-tech tools and gadgets they can use for everything from art to hobbies to their own small businesses.

Shortages of personal protective equipment have forced health care workers to wrap themselves in bandannas and garbage bags as they care for the sick. Cooper realized that his idled workshop held the perfect tools for making one key piece of safety gear: face shields.

Face shields offer a protective barrier between a doctor or nurse and the patient coughing in their face. After a bit of tinkering, Cooper realized that some of the equipment around the maker space — 3-D printers, a three-hole punch and the transparency sheets you can buy at office supply stores — could produce face shields almost as good as the real thing and a lot better than a bandanna.

While volunteers started printing face shields on their home 3-D printers, Cooper reached out to hospitals around the state to see if anyone could use some extra supplies.

Everyone, it turned out, could use some extra supplies.

Cooper heard from urban hospitals, rural hospitals, the VA, small clinics, nursing homes, hospices and individual nurses.

"Just in their e-mails, you can hear the desperation," he said. "We have yet to turn down anyone. As more and more volunteers come online, we're able to produce more."

At CentraCare in St. Cloud, face shields were some of the first supplies to run low.

"The entire supply chain is crazy," said Dustin Maddy, who is spearheading Centra­Care's hunt for personal protective equipment. "Some people are buying way too much. Some people can't get ahold of what they need."

There isn't a hospital in America that has everything it needs to battle this pandemic.

There aren't enough COVID-19 tests, there aren't enough ventilators, there aren't enough masks and protective gear. The further down the supply chain you go, the harder it is to get even basic supplies as big hospitals in distant states battle and outbid each other.

The supplies a hospital orders might not be the supplies that arrive.

"We'd source a million [units of personal protective equipment] and they'd say, 'Well, you get 50,000,' " Maddy said. "One of the first items that stopped showing up in quantity was our face shields."

Then Nordeast reached out with a few prototypes and a price that was hard to beat — free.

Hospital staff studied the Nordeast design, then jumped at the offer. Last week, Maddy traveled down to Nordeast's maker space on NE. Taft Street in Minneapolis.

"It was the coolest thing," he said. "I was in there talking with Tyler and there was this stream of just random hobbyists showing up at the door with bags full of 3-D printed face shields."

These makers, whose own lives and businesses have been disrupted by the shutdown, are spending countless hours to make precious medical equipment, just so they can give it all away.

Some donations arrive with love notes inscribed on the headbands for front-line medical workers: Thank you, thank you, thank you so much.

Maddy drove back to St. Cloud with more than 500 new face shields.

Nordeast shared the design files with St. Cloud State University. Now banks of 3-D printers and laser cutters in a school lab are churning out an assembly line of safety gear for the hospital.

"We were getting printed hundreds of face shields a day," Maddy said.

With a steady supply of help close to home, CentraCare no longer needs equipment from Nordeast. But a lot of other facilities do.

Those who can't 3-D print, donate. Nordeast has raised more than $5,000 of the $7,000 it needs to cover the cost of the raw materials that go into the face shields.

If you're with a medical facility that needs protective gear, or if you want to donate to help out, visit nordeastmakers.com/donate.