It’s the details that make Calvin Coble’s four-car train design so much fun.

The engine uses an ice cream swirl to look like smoke clouds billowing from the chimney. The second car is filled with coal, while the third holds hay. And the caboose, on its roof, carries a police car.

At age six, Coble, the Lego train’s engineer, declares the last car is called the “boose,” and that the train’s yellow block cargo is actually golden hay.

“I like to imagine them as gold,” said Coble, who added gates to make sure they don’t fall out of the train.

Coble’s original Lego build is entered into the B&O Railroad Museum’s Brick Build-Off, a Lego construction competition where competitors submit railroad-themed builds.

The best builds are chosen to be displayed in the museum, alongside the large locomotives they are often modeled after.

Next week, it will be the job of visitors to the museum to choose the Brick Build-Off winners.

You wouldn’t know it by just looking at 14-year-old Nicholas Clark’s build, but the train in his model of the historic Ellicott City train station moves back and forth.

Clark managed this using a Lego-compatible motor — the train is built around it — to power the back wheels through a battery pack attached to the hood. Tires act as bumpers at both ends of the track to absorb the impact of the train as it chugs back and forth.

Competitors can build anything original they’d like, and kits are not allowed. The only requirements are that their builds must be railroad-related and able to fit on a 6-foot folding table.

Sam Hughes, education director at the B&O Railroad Museum, said that many of the builders are able to use the Brick Build-Off as an opportunity to connect two of their passions: trains and Legos.

Roman Vaccaro is 5 years old and he’s entered his Lego build modeling the C&O 490 locomotive that is on display in the museum.

Vaccaro has been into trains his whole life and built his first Lego train at three. If you’re wondering how a 3-year-old learned to build his own Lego train, Vaccaro started with kits and YouTube videos that demonstrate how to make them.

This early training allowed him, without any plan, to build the train he submitted to the Brick Build-Off in less than two hours.

The Brick Build-Off began last year when a company that hosts traveling Lego expositions reached out to the B&O Museum for a collaboration.

The company dropped out this year, but Hughes and his team wanted to continue holding the competition to leverage young people’s excitement for constructive games, and to build a community of railroad enthusiasts.

The Brick Build-Off is a way for young folks to engage with the massive locomotives, trains and cars they see in the museum using something as simple as Legos, Hughes said. “It’s about getting young people invested in creating the big things they see around them in the world.”

This year’s competition has more age brackets than last year’s, with categories for 10 and under, teens, 18 and over, and groups.

The submission period has closed and Hughes and his team will review them and choose finalists to be displayed in the museum.

Anyone who visits the museum between July 13 and July 20 can vote on a winner in each category.

The voting chips? Legos, of course.