Elena Bonvicini didn't set out to start a multimillion-dollar denim brand worn by the likes of Taylor Swift, Gigi Hadid and Kendall Jenner. She just liked thrift shopping. 

Every summer as a teen, the Southern California native would go to Wisconsin to see her grandparents. She'd visit thrift stores in the area and rifle through the denim selection, searching for Levi's that she could fashion into cutoff shorts for herself and her friends.

Originally, it wasn't supposed to be a business. Bonvicini had fun making the cutoffs and, as she told CNBC Make It, "always loved having things that no one else had." But that changed when she was back at high school and someone asked about her shorts. 

"I got stopped by a girl who was two grades below me and she was like, 'Oh my gosh, where'd you get those shorts?'" Bonvicini, now 25, explains. "And I said 'Oh, I made them!' And she was like 'Can I buy a pair? Can you make me a pair?'" 

Bonvicini had never sold clothing before, so she relied on her best "guesstimation" to set the price for her first sale at $30. More girls started asking Bonvicini about the pants, and the young designer realized that she had a business on her hands. 

Bonvicini was soon selling hundreds of reworked vintage pants to classmates from her high school and other schools in the area. Every Friday, she would set up shop in her gym locker room and sell jeans for $10 each. 

"I would lay them all on the locker room floor and the girls would come and have a try-on party," she says. "This was before Depop or Poshmark, so it was kind of a new idea to be upcycling and buying clothes from the thrift store and making them cute."

Even charging her friends and classmates just $10 or $30 for a pair of jeans, Bonvicini turned a nice profit. 

"In the Midwest I was buying [the jeans] for 50 cents. In some places, you could buy a trash bag filled with anything for $8. I could probably fit 20 pairs of jeans into one bag," she says. "There was a huge profit margin there." 

When shorts were out of season she asked her mother for a sewing machine so she could try her hand at taking vintage boy's jeans and turning them into something she and her teenaged customers could wear. Her mom agreed to get her a $300 machine on one condition: they would go to their local Joanne's Fabrics for sewing lessons. 

By the time she was approaching her high school graduation, Bonvicini was determined to grow her brand. She created an Etsy account the day she turned 18 and set out to use social media to help turn EB Denim into the next big thing.

Taking EB Denim to the next level

Early on, Bonvicini knew that her best bet to get more eyes on her designs would be to get popular people wearing them.

"I decided that I wanted to reach out to people I thought were cool on Instagram, message them, find their email," she says. "I didn't care if they posted it or not. I just wanted them to have my design." 

The gifting strategy paid off. The teen founder was shocked to not only hear back from influencers and style icons like Chiara Ferragni and Danielle Bernstein, but also see them post themselves in her clothes. 

"She's like the Kylie Jenner of Italy," she said of Ferragni. "I didn't expect for her to DM me back. I reached out to every single email that I found, and her assistant ended up replying." 

The exposure proved to be an immediate boon to her business. 

"I started seeing traffic coming through our website and an immediate return on investment," she says. "It was just immediate sales. That's when I really knew that I actually had something." 

At college, Bonvicini worked diligently to expand EB Denim. She hired an assistant to help her ship orders that came through her website. Her weekends would be spent acquiring hundreds of pairs of jeans at the Melrose Trading Post or Rose Bowl Flea Market and building relationships with suppliers. 

She added several new designs for reimagined Levi's, upped her inventory and kept gifting jeans to celebrities and influencers. She also continued selling to classmates — this time, to sorority sisters at USC. Gone were the $10 jeans. Now, she was charging $220 for her more refined product. 

"I would do trunk shows at my sorority house and I would invite all the girls," she said. "I did this thing where if they posted on their Instagram story they would get 10% off at checkout. So every single girl was posting it, putting it on their feed." 

Bonvicini acquired each pair of jeans for around $20 and spent $14 reworking them before washing them in her home washing machine. To keep up with so much demand, Bonvicini had hired seamstresses to tailor the jeans to her specifications. On her best day, she says she sold $12,000 worth of pants in just a few hours. 

With momentum building behind her brand, she took her profits and reinvested them into her company by hiring a PR agency to help her with influencer outreach. 

"I wasn't looking for it to be a money-making machine," she says. "I always knew that in order for it to grow into this vision of what it could be, I needed to put everything I could back into it." 

"There was a huge world of people I didn't have access to and couldn't get a hold of," the 25-year-old adds. "Why are these people going to respond to a 19-year-old? I got really lucky at the beginning. [My firm] got me on Kylie Jenner, Hailey Bieber, Gigi Hadid, Bella Hadid." 

This exposure also got EB Denim into high-end retailers like REVOLVE and Selfridges. By the time she was a junior, she says EB Denim was bringing in over $1 million in revenue and had a small handful of employees and interns. The brand was doing so well, in fact, that she was debating leaving USC altogether. 

"I wanted to drop out," she says, "but my mom was like 'You better stay your a-- in school!'"

Instead, she focused her studies and tried to apply everything she learned to her business. 

"Any time we had an entrepreneurship assignment, I would make it about my brand," she says. "It made me think about everything in a more professional and sophisticated lens, which I think really helped me in so many ways." 

The Taylor Swift effect

EB Denim continued to grow over the next few years, adding dresses, t-shirts and jackets to its offerings. It continued to be a favorite of influencers and tastemakers.

Everything came to a head after the 2023 Video Music Awards. 

Bonvicini team had been notified by Taylor Swift's stylist that the pop star would be wearing one of EB Denim's items, but they didn't know which one or when. Then, while she was out at a Fashion Week party, Bonvicini phone started to buzz.

"I remember looking at my phone at three in the morning and someone had sent me a picture of Taylor Swift walking out of a VMAs after party wearing the dress," she says. "I was like 'Oh, that's so cool.'" 

"Then the next morning I woke up so hung over and saw [so many] Shopify notifications," Bovincini continues. "Mind you, this dress is like $500. I was stunned."

Thanks to the heads up, the brand had press releases ready to send out to outlets as EB Denim was featured in countless articles and roundups chronicling Swift's style.

EB Denim is on track to bring in $3 million in revenue this year, a far cry from its $30 start. Despite her success, Bovincini sometimes has a hard time believing how far she's come.

"I have imposter syndrome," she says with a laugh. "I don't think I even now feel like a businesswoman."