Items recovered from the National Building Museum Beach (Museum staff/courtesy of the National Building Museum)

When all the white plastic balls had been packed away, the National Building Museum was $433.24 richer.

That's how much in cash and coins volunteer coordinator Kristen Sheldon and her troupe of helpers recovered from the bottom of the ball pit ocean once "The Beach," the museum's blockbuster summer art installation that attracted 180,000 visitors, had been removed. And that's just the American money, not counting several "[e]uros, some loonies, some Thai money," said Sheldon.  There was also $31 in "bills that we found halves of" some of which they reconnected through matching the serial numbers: "Reverse counterfeiting," as Sheldon called it.

[Lost something at the National Building Museum's Beach? It's not the only phone in the sea.]

When I wrote about the items that had been lost to the Davy Jones' Locker of the ball pit last week, readers wrote in to share their own missing items, from pairs of glasses to a child's tooth. Now that the balls have been boxed away -- given to the Dupont Underground for a future art installation -- Sheldon is ready for the final push in her quest to reunite Washingtonians with their long-lost stuff.

Missing a SmarTrip? Sheldon found 31 of them (she has returned them to WMATA). If you lost a baseball cap, chances are, yours may be among the 32 hats she pulled out of the deep. If you lost a wedding ring -- well, you may be out of luck.

"We weren't able to return five of them, which is a bummer," she said. There were nine rings reported missing, but only four were found.  "We tried -- oh my goodness, did we try. Everybody involved was so careful."

Volunteers sort through balls and debris (Museum staff/Courtesy of the National Building Museum)

She described a scene where volunteers meticulously picked through hairballs and carpet fibers to pull out earring backs and Lego figurine heads. They saved beads from broken jewelry. And in the process, they found some weird stuff: A beheadded Strawberry Shortcake doll. A cigarette butt. A Chuck-E-Cheese token. Two guitar picks. A book of 'Amphibians of North Carolina.' A plastic ear of corn.

"The Beach had a natural filtration system," said  Sheldon. "There was a gap at the bottom, and stuff would go underneath that."

[At the National Building Museum's Beach, you'll have a ball -- or a million of them]

Still, there were many things reported missing that never made it out of the beach, either because they were smashed to pieces under the tremendous force of the balls, or they were taken by another visitor.

"I thought we would find almost all of it," she said. "The fact that a lot of it didn't come up and I don't have a good explanation bugs me." She's been making some tough phone calls to people who lost jewelry or sentimental items that never surfaced. Sheldon has a message for those who visited "The Beach" this summer: "If anybody did take something that didn't belong to them -- other than cash, because you can't track that -- if they hear the stories of people who lost sentimental things, and want to do the right thing, they can bring it back to the museum, no questions asked."

So far, the museum has returned 60 percent of the items reported missing. Shoes, she says, are the easiest to reunite with their owners. She plans to hang on to items until the end of October before donating them to charity.

"I would have loved nothing better to return every little piece of every little thing to everyone," she said. "That's not realistic, I guess."

Still, even when Sheldon couldn't return an item, she has found some creative ways to make up for visitors' disappointment. Take the child who lost his first tooth in "The Beach." It was never recovered. But Sheldon is planning to "send a missive to that young man from the Washington Area Bureau of Tooth Fairies," explaining the tooth's disappearance. "I'll have a little fun with it," she said.