Twinkling lights, bustling shoppers, cold nights, larger-than-life pine trees and the suggestion of an imminent snowfall that will transform the gritty streets — that’s Christmas in New York city, the holiday where imagination reigns and visions of sugarplums can really dance, if only in a storefront window.

And no one knows that better than 23-year-old Sam Ashford, a frequent Island visitor whose imagination helped create the window displays at Saks Fifth Avenue.

This year’s display opened Tuesday night with help from ballerinas from the American Ballet Theater and a 3D light show on the façade of the store.

“The windows are beautiful,” Mr. Ashford said in a telephone interview from Manhattan on Tuesday before the grand unveiling took place. A recent graduate of Cooper Union in New York city, Mr. Ashford has been helping with Saks window displays for four years. He said he has been working on this year’s display since September.

The theme is the Land of the Bubble Makers, based on a book sold at Saks titled Who Makes the Snow? The story follows a little girl named Holly who arrives at Saks Fifth Avenue with her parents, and leaves them for a journey through the store. She finds a group of abominable snowmen on the roof of the department store and a world of bubble people in caves cranking out bubbles in the basement.

window display doll
Last year’s holiday window at Saks Fifth Avenue. — Karen Ashe

“It tells a story as you go around, one leads to the next,” Mr. Ashford said.

The bubble people in the displays show off the designs of Stella McCartney, Marchesa, Proenza Schouler, Alexander McQueen and the like, but beyond the fashion is Mr. Ashford’s art.

This year, he helped carve large Styrofoam caves that go around the circumference of the building’s windows. He attacked big blocks of the strange white material with saws and created snowmen to match. He welded chandeliers together, reused from last year, and for one window built tubes of colored water and air bubbles “so it looks like bubbly ducks everywhere.”

He also made spiral metal shelves, painted them with gold leaf, and decorated them with bubble drops, creating an environment with “weird reflection stuff going on.” Products now line those shelves.

Mr. Ashford worked with a crew of dressers, a mannequin squad, a lighting team and carpenters to design the display. He said he enjoys the teamwork.

“I like doing it, I like the people I work with, I like building things and figuring out how they work,” he said. “It’s funny because the designer sends out one page of instructions, and we figure out how to do it together,” he added.

“I’m an ant,” he said of his role in the overall project. But this ant helped build 36 windows around one of the world’s most famous department stores.

A self described “shop boy” in the Saks studio in Queens, Mr. Ashford took his love for welding and built the entire metal shop at the studio. Metalwork may have been his favorite class in school, but he stops short of labeling himself as a specific type of artist.

“A lot of people go to school for art and they go, I’m a painter, I’m a sculptor, but how do they know?” he said. “I’m a dabbler.”

While the bubbles, glitz and glam is always fun, Mr. Ashford acknowledges that the work itself can sometimes be monotonous.

“If there’s a chair in the window or three of them, each chair has 10 pieces; that right there is 30 pieces for the window times 36. That’s a lot, especially when it has fine curve cuts,” he said. “Everything has to be perfect.”

So perfect that the department stores in the area, including Bergdorf Goodman, Henri Bendel, Barneys New York and Macy’s, are all quietly competing for best window display every year.

Window shopping takes on new meaning when it comes to the department store displays, but now that the Christmas season is in full swing and the last Styrofoam snowman is safely secured, Mr. Ashford can turn his attention to other endeavors.

That means spending as much time as possible with the Occupy Wall Street protesters in Zuccotti Park. Microphones have been prohibited in the demonstrations, but Mr. Ashford found his own way to have a voice — through an eight-foot tall giant papier-mâché megaphone.

He brought it to the Times Square march several weeks ago, but holes in the sculpture caused rain to get in and cave in on itself.

He is now busy making foam barricades.