Amanda Bynes Crashed Michael Costello's Launch Party

Michael Costello - P 2015

Michael Costello - P 2015

Even the designer was taken by her surprise appearance as he celebrated his pre-fall collection.

When Amanda Bynes makes a public appearance after keeping out of the limelight for several months, you know it's for something good.

On Thursday evening, the 29-year-old stepped out in a white lace bodycon minidress and black pumps to toast the launch of Project Runway alum Michael Costello's pre-fall capsule collection. The soiree, hosted in downtown L.A., showcased Costello's latest shimmering, sexy designs, which featured the sheer and body-hugging elements that have made him a favorite among clients including Kim Kardashian and Lady Gaga

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Bynes, who briefly attended FIDM and has design aspirations herself, lavished compliments on the designer before taking requisite selfies and exchanging numbers. "I thought that was so cool that she was such a huge fan!" Costello told Pret-a-Reporter of Bynes' unanticipated appearance. "We talked for a little bit, she’s such a sweetheart, she’s such a nice girl."

Though she hasn't hit the red carpet since 2011, it's easy to see why the former child star — as well as singers Nicole Scherzinger and Aubrey O'Day — felt the need to see the collection up-close and personal. The bold black-and-white gowns and jumpsuits, made of sheer fabrics hand-sewn with intricate, abstract patterns of sequins, had all the dramatic flair you would expect from the man who pretty much invented the Naked Dress with Beyonce's 2014 Grammys look.

"I always loved showing skin. I love sexy stuff," said the designer of the collection he named "Nirvana." "I felt like [the dresses] were goddesses, like they were just little pieces of romance."

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One look at the sexy ensembles, many of which featured plunging deep-v necklines, bold shoulders and theatrical capes, and it's easy to get a feel for the designer's celebrity inspiration. When asked who he'd love to see in the collection, Costello responded: "Jennifer Lopez and Angelina Jolie. Those are the two people that I’ve never dressed. Yet."