Christian Siriano is a red-carpet regular. The designer had a hand in creating some very magical, best-dressed moments of awards shows past. This recent season of high-stakes step-and-repeats was no exception for the designer, but the last round was particularly noteworthy — and not just because it happened to be the Academy Awards. There was a pretty interesting (and involved) story behind one of Siriano's looks for the evening. In partnership with Stella Artois and Water.org, Siriano whipped up a trio of gowns for Maria Menounos to wear to the Oscars. They were all inspired by a set of limited-edition chalices the Belgian brewing company created to raise awareness about issues surrounding women's access to clean drinking water across the globe. (Stella Artois donated $6.25 of every $13 chalice sold to Water.org, which provides one person with five-years worth of clean drinking water.) "I’ve always been about making a fashion statement by leaving my mark on the red carpet," Siriano said in a statement. A philanthropic element is certainly one way to take the step-and-repeat conversation a step further. Out of the three styles Siriano crafted for the occasion, Menounos ended up donning an embellished, silver off-the-shoulder style at the awards ceremony and the Vanity Fair after-party. The story of Menounos' custom Siriano gown doesn't end there: The one-of-a-kind piece is currently up for auction, with all proceeds going to Water.org. Before the red carpet was even rolled out, our friends at Visionaire visited Siriano at his New York atelier to watch the magic happen firsthand. Watch the evolution of a gown, from sketch to mannequin (and a behind-the-scenes look at the designer's colorful studio), above.