On the cool marble floor of the Great Hall of the National Building Museum, Sydney Katz is building Dorothy’s ruby slippers out of cans of baked beans. She leans back to scrutinize the structure. “I mean, it’s definitely dipping a little, but we’ve got this really thick half-inch cardboard that’s very strong because of all the corrugation inside. As long as no one bumps into it, it should stand.”

Katz, of Georgetown Architecture firm Barnes Vanze Architects, explained how her firm came up with its submission in the 2013 Canstruction contest: “Last year we did the Grand Canyon, and it took a very long time. And it was huge. So this year, we decided we should do something we felt comfortable building. The theme is the National Mall, and we didn’t want to build a museum with a big box.” She said her team decided to build the ruby slippers because they are on the Mall, displayed at the Museum of American History. “It’s more fun than a building, and it’s different — no one else is doing it.”

For the architect and design teams in the contest, the building is part fun and part competition, all in the name of fighting hunger: at the end of the contest, the cans are donated to the Capital Area Food Bank. The contest, sponsored by the Washington Architectural Foundation, is the food bank’s largest food drive.

“Over the years, since ’98, we’ve put together enough to feed about 500,000 people,” said programs manager Beth Judy, who runs the contest for the foundation.

Noting contributions from sponsors such as Safeway, which discounts and ships the food, Judy said, “it’s just really a great effort — hundreds of people put this together. It’s a fun project within the architectural community. It’s part of building the city — we’re giving back.”

Projects for this year’s Canstruction contest are displayed at the National Building Museum. (Liz Vance)

The architectural teams’ work starts long before the first day of building. “We’ve been working on this for about two months,” said Eva Lynch of WDG Architecture.

Her team co-leader, Tom Zych, said, “The trickiest part is, first of all, making sure your can count is right. There’s so much stuff to assemble. We’re designing things, we’re printing stuff out, we’re laying out boards. There’s just a lot of prep work.”

The WDG team, like several teams this year, created its own version of the recently scrapped Hirschhorn Bubble proposal. WDG’s version included whimsical panda ears and a tail.

“It’s meant to be kind of a fun take on it,” Zych said. “Something that D.C. would actually accept, as opposed to modern architecture.”

Paul O’Connell of EYP has participated in the contest for 10 years. “I think the best part is just actually coming and doing the buildout. It’s a lot of fun, it’s a good cause, and internally we do some fundraising. We raise half, and our company raises the other half.”

O’Connell said his team’s toughest challenge was recreating Philadelphia’s Love monument last year. “We used tomatoes and chili peppers. It was tricky to stabilize it. That one took us a long time to build and figure out,” he said.

On Labor Day, visitors to the Building Museum found relief from the humidity outside as they wandered around the completed Canstruction sculptures that filled the cool, marble-arched Great Hall.

“This is just so fantastic,” said Susan Cowles, who has seen a number of previous Canstruction displays. “I’m pretty sure that I attended the very first Canstruction in the ’90s in New York City. I just admire it. I admire the enthusiasm of everyone who’s doing this. They’re also judged on the meal that they can make out of the canned goods; that’s one of the categories. I think it’s just very clever.”

MeiMei Barna, 7, concurred: “It’s awesome! It’s so awesome that they’re balancing on the faces of the cans, on the top parts of the cans.”

Barna and her family, visiting Washington from Hershey, Pa., happened upon the exhibit by accident. MeiMei’s brother Ethan, 10, chose MV + A Architects’ replica of the Jefferson Memorial and Tidal Basin as his favorite.

“I liked this one,” Ethan said. “I find it very resourceful, the way they made the waves from the backs of the tuna cans.”

Darrel Rippeteau of Rippeteau Architects has been chairman of the Canstruction program for the Washington Foundation of Architects for the past 10 years. “Young people generate the excitement through their designs, generate funding by encouraging their employers to contribute financially, and generate public notice by putting on something so remarkable to look at,” he said. “The end result is food transferred directly to pantries so people can eat it. It’s the perfect grass-roots effort.”

Photos of each structure are on the Capital Area Food Bank Web site, www.capitalareafoodbank.org. Visitors to the site can donate $1 per vote through Saturday.