Steve Case, left, Ted Leonsis, center, and Donn Davis — all former top AOL executives and entrepreneurs — at the Revolution Growth Fund offices in Washington. (Jahi Chikwendiu/The Washington Post)

Revolution Growth, the local venture fund known for its tech-savvy founders Steve Case and Ted Leonsis, is making a $40 million bet on a very low-tech investment: Northern Virginia-based ­T-shirt company CustomInk.

CustomInk allows customers to design T-shirts for family reunions, small businesses, religious groups or student associations online. Picture 50 T-shirts emblazoned with “The Smith Family Reunion” or 150 baseball caps marking the local 5K fundraiser.

The company is in Revolution’s sweet spot, said Leonsis, Revolution’s co-founder and owner of the Washington Capitals.

“It’s a next-generation social shopping company,” he said.

The company was founded in 2000 by Harvard math whiz Marc Katz and two former classmates. Katz, 37, is president and the largest shareholder in CustomInk, which grosses nearly $200 million a year on the sale of 20 million T-shirts. The company employs more than 800 people.

Leonsis, who will take a board seat as part of the investment, and Katz declined to disclose what percentage of the company Revolution will own or how much they believe CustomInk is worth.

Katz said the $40 million will help fund the company’s expansion, which includes a move to more spacious offices in the Mosaic District of Merrifield, Va., in January. It also will fund the expansion of a CustomInk operation in Reno, Nev., a production facility in Charlottesville and the opening of a new facility in Dallas.

“The capital and guidance from Revolution should be really helpful with all that,” Katz said.

Leonsis, who is the majority investor in Monumental Sports & Entertainment, said he learned about CustomInk several years ago and became familiar with the company when his two children bought T-shirts through the company’s online site. He approached Fred Schaufeld, his partner in Monumental and an investor in CustomInk, to make an introduction to Katz.

Leonsis then began an eight-month courtship of Katz, including hosting the CustomInk founder in the owners’ box at Verizon Center.

“Marc is a remarkable entrepreneur and is a strong operator,” Leonsis said. “He built a company of this scale and size locally, and it was right down our strike zone.”

Katz drives the business to profitability on efficiencies and customer service that simplifies the process for selecting and decorating custom T-shirts. Most of the company’s costs don’t kick in until an order is placed. CustomInk representatives talk to customers at length, walking them through the process and assisting with design. The company has artists on staff to help on special requests.

CustomInk has several growth initiatives, including Booster, which helps customers raise money and support for their causes. The other is Pear, which involves selling corporate “sponsorship rights” that allow customers to put a company logo on their T-shirts in return for a lower cost per T-shirt.

“That’s like naming rights,” Leonsis said. “It’s very, very targeted, and the consumer opts in.”

CustomInk follows a half-dozen recent local investments by Revolution Growth, a $450 million Washington-centric fund that was begun with great fanfare two years ago by Leonsis, Case and Donn Davis, all three of whom made their names and fortunes at AOL during the late 1990s.

Revolution has been targeting a new investment category that the principals call “speed-up capital,” which is designed to expand companies worth $100 million into ones worth $1 billion or more.

Although Leonsis, Case and Davis are tech-savvy millionaires with strong operating backgrounds, the jury is out on whether the strategy will pay off for the fund’s three-dozen investors.

Earlier this year, Revolution invested in Optoro, which develops software that enables big-box retailers to redirect their unsold or returned inventory, from laptops to blenders, to online sites such as eBay and

Revolution led an investment last year in FedBid, which attempts to make it easier for government agencies and businesses to buy things. It also invested in Echo360, which is trying to help universities move their education content, including classroom instruction, online.