Virtual paper dolls? DIY fashion magazine? Shopping wish list? It’s difficult to describe exactly what Polyvore — an online tool that enables users to design and share sartorial collages — is. With more than 13 million visitors each month, the five-year-old Web site has tapped into a fan base that doesn’t just want to digest fashion trends — it wants to create them. The Washington Post partnered with Polyvore in January to launch Oscars Remix, an Academy Awards-themed contest that offered one winner the chance to play style editor in the pages of The Washington Post.

After receiving more than 7,000 entries featuring everything from flapper-length pearls inspired by “The Artist” to Angelina Jolie’s Versace-framed leg, we chose an ethereal collage with Michelle Williams (above) by Anamarija Brstilo of Split, Croatia. We gave Brstilo a final challenge that’s decidedly more Washington — create a look (below) for Michelle Obama’s official dinner Wednesday with British Prime Minister David Cameron and his wife, Samantha.

Brstilo, a 29-year-old mother-to-be, works as a marketing assistant for the U.N. Development Program’s energy efficiency project. Her day job has nothing to do with fashion, and she uses Polyvore to escape into a “secret world” where she can immerse herself in her hobby.

“The fashion world is often very far away from us regular people, whether it’s because of our size or because of money,” Brstilo says. Polyvore is “a great way to try out new things and maybe inspire yourself to do something like that in your own closet.”

Brstilo has an eye for detail and an ability to tap into the aesthetic of individual women. The classic sets she designed for Williams and Obama adhere to one of her core fashion principles: Less is more.

See more finalists from the Oscars Remix challenge:

Finalists in the Best picture challenge

Finalists in the Best actress challenge

Finalists in the red carpet challenge

Finalists in the red carpet to real life challenge

View Photo Gallery:  See some of the Oscars Remix: Best picture challenge submissions.

View Photo Gallery: See some of the submissions in the best actress challenge.