The Dover, N.H., company makes liquid containment bags used by the space agency, and executives see the president’s proposal as an opportunity for greater commerce with the federal agency.

“We want to be the NASA bag maker,” said Evan Welch, founder and chief executive. “If there are to be more projects and voyages, we want to be part of them.”

Welch Fluorocarbon, a private company that employs about 25, has developed a niche that is about as thin as the products it produces.

It is an example of a profitable company that has bootstrapped its way to success over its 19-year life. And it is looking for growth in the future.

Welch Fluorocarbon produces tiny, super-thin thermoformed parts for critical applications.

In fact, it doesn’t develop products as much as it produces them for customers.

One area in which the company developed a consistent revenue stream is with the space program. NASA, or its purchasing agents, came to Welch about a decade ago seeking bags into which astronauts could urinate.

Industry analysts say Welch is the sole supplier of this product, which reportedly takes 28 steps to make.

“NASA has an interest in monitoring the human body,” said Welch, a Marblehead native who studied at Claremont College in California.

“They want to know how much liquid goes in (to the body), and how much comes out. Our product enables them to determine how much liquid is evacuated.”

The company’s other products include corrosion barriers for air regulators in gas masks, and a liner of DuPont’s Kapton polyimide for a smoke hood used by commercial flight crews.

Many of the company’s contracts come from referrals from DuPont.

“A lot of our business development comes from word of mouth,” Welch said. “We have done much work with DuPont, and their recommendation to other companies has helped.”

DuPont has proved a strong source of revenue, but perhaps not as much as a manned trip to Mars will.