Selena Gomez, Vanessa Hudgens, and Ashley Benson spend a good deal of screen time in Spring Breakers in neon bikinis, crop tops, and short-shorts—the film is about spring break, after all—and there’s one woman they can thank for their fun and flattering beach closets: costume designer Heidi Bivens. Bivens created each character’s collection of perfect (and often pink) two-pieces, and fans have loved the looks so much, she even collaborated with Opening Ceremony on a Breakers-inspired capsule, complete with the film’s signature unicorn emblazoned on tees, tanks, towels, and string bikinis. That’s why we caught up with the designer, who spilled on Selena and the girls, what it takes to wear a two-piece around the clock, and what you should be looking for in a suit for your own spring break adventure. Click the jump to read our exclusive interview, and check out Spring Breakers in theaters today!

InStyle: How did you pick the looks for each actress?
Heidi Bivens: I work on creating a “closet” of clothing for each character’s wardrobe before the actresses arrive on location. The styling direction for the costumes is ultimately a collaboration between the costume designer and the director, but the actresses definitely have input since they must believe that their characters would wear the costumes we choose for the film.

How did they feel about their very revealing costumes?
At first the actresses wanted to discuss whether or not they would wear the swimwear for such a large part of the film, but when it was time to establish costumes on screen, they agreed with the director’s vision and wore the bikinis as scripted.

What was it like working with Selena, Ashley, Vanessa, and Rachel on such a risk-taking film? 
When shooting on location, the crew and actors become like a surrogate family of sorts. It was exciting to see the girls take on these less-than-perfect characters. I made sure I was available to them for emotional and professional support if they needed to talk about any concerns they had regarding a scene and how the costumes (or lack of!) were effective.

What are some of your favorite swim brands in real life?
I love Shimmi, O.C. “Spring Breakers” collaboration, Eres, Lover, Alexander Wang, Victoria’s Secret, and Tory Praver.

How do you pick the perfect bikini?
Try lots of different styles. Swimwear has minimal hanger appeal, so you really must try on as many styles as you have patience for to find the perfect fit and style. Identify your best asset and body trait, and capitalize on whatever you like best about your figure.

Plus, see Selena at the Spring Breakers premiere and more.

SELENA'S FASHION

MORE:
Selena Premieres Spring Breakers in Venice
Ashley Tisdale Supports Vanessa at the LA Premiere
See Selena, Vanessa, and Ashley On the Beach Set!

— Violet Gaynor