PORTLAND, Maine — For years, David Stone traveled the world as a high-tech business consultant, often missing his five children’s birthdays and other life events.

Like many business travelers, he’d buy gifts at airport malls and eventually turned to ordering plastic gift cards for his kids. But the cards often arrived late and weren’t terribly personal, said Stone.

“That was my ‘a-ha’ — there had to be a way to make it more personal and efficient,” said Stone.

Stone worked on the idea in the attic of his Falmouth home, and in 2008 founded the company CashStar Inc.

CashStar is forging into the “post-plastic card era,” as Stone puts it. The company provides the back-end processing of electronic gift cards for a who’s who list of retailers. When you go to the Williams-Sonoma website (or to Banana Republic, or Home Depot, or Staples, or Gap, or Best Buy, or many others) and buy an eGift card, the transaction takes place on CashStar’s servers, running on proprietary programming that uses fraud detection and prevention algorithms to ensure the integrity of the sales.

The eCards can be personalized with a message, photo and even video the consumer attaches to the gift.

The overall gift card market is pegged at $100 billion, with 70 percent of Americans having either received or bought a gift card. CashStar essentially takes the physical card out of the equation, with the goal of allowing consumers to buy an eGift card for anyone, at any time, for any amount, using any electronic device — from computers to tablets to smartphones.

“[Amazon founder] Jeff Bezos had a vision of changing how people buy books — we have a vision of changing how people give gifts,” said Stone. “We’re a transformational technology — transforming the world of gifting from physical to digital.”

Unlike many Maine ventures which often have difficulty attracting financing and growing beyond a small work force, CashStar has progressed well beyond start-up mode. Three years after its official founding, the company today has 70 employees and plans to hire up to 30 more this year. Over the past several years, the company has obtained $28 million in venture capital and private equity funding.

Stone wouldn’t disclose whether CashStar, a privately held company, was profitable at this point. But the 2011 holiday season saw overall sales up 300 percent year over year, he noted. CashStar makes money through a tiny percentage of each transaction.

While CashStar was the primary entrant into the market, there are now about a dozen competitors, said Stone. But, he added, four of the top six retailers in the United States were his clients. The other two, he said, were Amazon and iTunes.

The company has challenges ahead as it seeks to get to the next level, said Stone, and he discussed some of those issues with Sen. Susan Collins on Thursday when she visited the downtown business.

That next level, said Stone, is taking on new customers and further penetrating the consumer market.

The big challenge as CashStar seeks to grow is the relatively shallow labor pool for high-tech, midlevel employees, said Stone. The company is seeking project managers, programmers, mobile-computing programmers and customer service experts to work with CashStar’s “high-touch” clients and others.

It can be difficult to attract the right people to Maine and sometimes hard to find people with the right skill sets here, he said. It’s an increasingly obvious problem that’s been heard throughout Maine — the “skills gap” between jobs that need to be filled and the work force with the experience needed.

Stone does have some paid interns working for him who are getting experience while going through school. He has hired graduates from Maine’s public and private universities and has taken folks from other fields — such as building construction and even yard care — and has trained them to fill roles at CashStar.

“I keep turning over rocks and lobster traps looking for people,” he said.

When Stone first met with California-based investors about his idea, they immediately offered him $3 million in startup funds, but wanted him to launch the company there. He refused, convincing them Maine was a viable home for CashStar.

The state has a relatively strong talent pool of back-office payment processing experts with firms such as Wright Express, Unum, Blue Tarp, TD Bank and others, he said.

And Maine has a reputation for its strong work ethic and friendly, down-to-earth people, he said. That brand, he said, is attractive to CashStar’s big-name clients. The state should do more to build and protect that brand, he said.

The company is opening a California office and is considering a Boston-area office. Stone said he’d prefer not to open an office in Massachusetts and would rather have the jobs here, but being in Boston may allow him to hire the professionals he needs.

Any job he brings to Maine has an economic impact, said Stone. That doesn’t include just the wages and income tax, but the money those people spend downtown every day and the goods they buy locally, for example.

Collins suggested CashStar work more closely with the University of Maine to develop programs that graduate students with the skills the company needs. She said a jobs bill she proposed last spring contained proposals to tailor job-training programs so federal agencies work more closely with local colleges and companies to provide skills that actually are needed in the market.

“CashStar is the kind of company that the state of Maine needs to attract,” said Collins. “They could have located anywhere — they’ve chosen to be here.”