BALTIMORE – When Olympic skiing champion Lindsey Vonn needs custom-fitted workout clothes or cross-training shoes, she contacts Under Armour, her longtime sponsor.

"I've got a 3D body scan," Vonn said, "so whenever we need to make something custom like a new turtleneck they can get that going."

Most of the rest of us have not submitted to 3D modeling, in which sensors take intricate measurements that allow clothes to be made that drape just right. But Under Armour – and rival sports brands Nike and Adidas – are banking on a growing consumer appetite for shoes and apparel that look or feel as customized as a built-in cabinet.

"We see customization and personalization as the new expectation from consumers really," said Dave Dombrow, Under Armour's chief designer. "It's a very important topic to us."

The idea is to market a personalized approach akin to what the brands do free for their celebrity athletes – a Vonn, a Stephen Curry or a LeBron James – who often are closely involved in the design of their gear.

"It's definitely a hot trend," said Neil Saunders, an analyst with the research firm GlobalData Retail. "What they want to move to is mass customization where you have the same sorts of efficiencies of mass production but you allow people to personalize things.

"That's obviously a difficult balance," Saunders said. For now, customization remains "fairly niche," he said.

Under Armour, Nike and Adidas each has its own online platforms allowing buyers to choose materials, colors or splashy patterns to give their athletic shoes an individual look. For Nike, it's NIKEiD; for Adidas, it's Miadidas.

Under Armour's UA Icon allows users to customize some of the signature sneaker models of NBA star Curry – including adding their own uploaded pictures.

"What you see is people would take the most iconic shoe and be the most creative with them," said James Carnes, Adidas vice president of strategy creation.

The German brand's most customized shoe is the Stan Smith, a popular line named for an American tennis champion successful in the 1970s, Carnes said.

Adidas is using market research to tailor a line of themed shoes for six cities around the world. The design of the London shoe, which debuted in October for about $259, was influenced by customers who run to work. The running shoe is primarily gray – a nod, the company says, to "the streets of London." A Paris shoe has since been released, with models for Los Angeles, New York, Tokyo and Shanghai due out in 2018.

At Nike's SoHo store in New York City, the company says, customers can spend about 45 minutes choosing material, colors, lettering and numbers, and emerge with a sports jersey "completely tailored to you."

Oregon-based Nike also recently opened a New York studio where shoppers meet with a consultant to design patterns for a shoe that then can be produced for them in under an hour.

While Nike and other companies have long offered customers the ability to customize shoes online and have them shipped, producing the shoes on site that customers design distinguishes the studio.

The studio is open to members of Nike Plus, a loyalty club, who register in advance, a Nike spokesman said.

Receiving customized shoes online – from a variety of companies – typically takes weeks.

Baltimore-based Under Armour's website says it takes "no longer than five to eight weeks," depending on the model. Customers uploading photos to put on shoes are asked by the company to avoid "metallic and fluorescent colors as they do not print" and to note that "if your image is not large enough to cover the entire photo area, it will begin to repeat to ensure complete coverage" of the shoe.

"There are people out there who want to have a shoe made just for them," said Matt Powell, a sports industry analyst for The NPD Group.

"The biggest barrier to sustained growth is it takes so long to get the product," Powell said. "Every brand is doing this. They are making money here, but I don't see it as a big growth area or a significant part of their business."

Custom tailoring has always been part of clothing-making, albeit an expensive niche in recent decades.

Outside the sports world, some new outlets – such as Alton Lane and Bonobos – are pitching customized clothes.

"A company like Bonobos has done very well because it's centered around personalizing products," said Saunders, the GlobalData analyst. "Wal-Mart bought them (last year) because they wanted a stake in that area."

But customizing remains expensive for retailers, and Saunders said not every consumer needs to have clothes molded to their forms.

"Some people just don't care," he said. "With athletes, everything must fit properly. Most people on a casual bike ride or a jog around the block aren't really driven by the extreme sort of fitting athletes demand."

Under Armour athletes can get body scans at the company's lab in Baltimore. The lab also contains robotic machinery and 3D printers that make sneakers, although not in mass quantities. Much of the space in the lab, called the Lighthouse, is devoted to improving manufacturing techniques and testing apparel and footwear lines before the products go into full-scale production.

Under Armour also is testing manufacturing ideas there for what it calls making local for local, designed to bring manufacturing closer to where its makes sales.

The three big sports brands also are seeking to personalize their relationship with customers through wearable technology – devices that monitor performance and health.

On Feb. 1, Under Armour will introduce the HOVR Phantom and HOVR Sonic – running shoes with optional sensors linking via Bluetooth to the popular Under Armour app MapMyRun.

In a recent demonstration provided by Under Armour, the app began to link up as soon as the Phantom was pulled from its box. "Keep your phone near your right shoe," read a notification from the app, which depicted an image of the red Phantom shoe as the connection was made.

The app collects information on runners' stride length in inches, steps per minute and minutes per mile, among other data. The Phantoms and Sonics with the sensors cost $140 and $110, respectively.

In 2016, Under Armour created a "smart' shoe with sensor technology for Jordan Spieth, its top golfer. He wore it during the U.S. Open that year and it incorporated the same devices found in the company's Gemini line that was available to the public. The sensor, in one of the shoe's midsoles, showed Spieth took 13,541 steps to complete the 18-hole course.

Wherever possible, Dombow said the company wants its consumers to benefit from the same technology its professional athletes use.

"With advancements in technology, the cost comes significantly down," Dombrow said. "Things are advancing very rapidly."