When thousands of geeks descend on San Diego Comic Con later this month, many will pause at the Lego booth to admire the toy company's latest large-scale model: a human-sized replica of the Flash, in brick form.

What onlookers won't see are the months of preparation that go into large-scale brick-building. It's a process that takes place about 2,500 miles across the country at the Lego model shop in Enfield, Connecticut, where a small team of builders tirelessly to produce pieces that delight brick fans worldwide.

This year's Comic Con superhero comes courtesy of Master Builder Mark Roe, a 23-year model shop veteran.

Roe began his tenure at Lego just a few years out of art school. As a builder, he caught the eyes of the model shop's then design managers, impressing them enough to make the jump to designing himself. Now he's one of just a few master builders at the Enfield shop, where he's designed the likes of Wonder Woman and San Francisco Giants pitcher Madison Bumgarner.

Long before model builders begin to piece together the brick-version of DC Comics' latest superhero star, the process begins with a meeting between Lego and the film studio. There it's decided which DC superhero will be immortalized in brick-form and unveiled at San Diego Comic Con. This year, ahead of November's Justice League release, it's the Flash's turn.

The design process begins with computer animation. The studio gives designers like Roe access to 360-degree scans of the actor dressed in his or her costume— this time of Justice League's Ezra Miller dressed in full Flash gear. Then Roe uses Autodesk Maya — a 3D computer graphics software — to arrange the model, limb by limb, into poses that might translate in real life.

"It's kind of subtle, because you have to think about how a person stands," Roe said, using his mouse to adjust the legs on 3D Flash.

The model shop designers offer DC Comics three pose options, and the studio has final say on which design moves forward. Though Roe was partial to pose two, DC went with pose one. Image: mia johnson/mashable

After DC selects a pose, Roe moves the 3D model into Lego's proprietary brick-building software. With just a few clicks, the program generates a rough mock-up of the model in brick form.

As Roe gets to work adjusting costume details and perfecting facial features, his background in 3D design and illustration comes to the forefront.

He'll sometimes hand-sketch a portrait on paper to get a better sense of the model's facial features. While designing the Flash, he dug into the model shop's brick stash in order to build a mock-up of the superhero's face and mask. It took Roe 60 hours in total to fine-tune this year's design.

Tools at a builder station located in the center of the model shop. Image: Mia johnson/mashable

Once a design is completed, model shop builders get to work bringing Roe's vision to life. Seated at work stations in the center of the shop, builders assemble the models, piece by piece over the course of a few weeks.

Builders use a proprietary solvent that melts the plastic bricks together, ensuring the piece stays as one, and custom steel armatures within the sculpture provide extra support. The result is a solid model that can handle the long trip between Enfield and San Diego.

The Flash in its final form. Image: mia johnson/mashable

The final model, including its platform and internal steel armature, weighs about 150 pounds. Image: mia johnson/mashable A team of two builders assembled the model in two-and-a-half weeks. Image: MIA JOHNSON/MASHABLE

No job is without its challenges, however— the Lego model shop included. For example: The time the team designed and built a large-scale model of San Francisco Giants catcher Buster Posey, only to step back and realize that the piece was just a little bit smaller than expected.

"We finished the whole thing, stepped back and looked at him, and [realized] this is probably high school age Buster Posey, not man Buster Posey," Roe chuckled. "You could not tell on the screen. They gave me measurements...it all looked good, but it just did not work."

(Don't worry— after a little trial-and-error, Posey got his Lego model in the end.)

Smaller mistakes don't require quite the overhaul. When a brick on the Flash's back appeared out of place, Roe says he was able to design around it. And when a brick really needs to come off, builders grab the pliers or, if need be, a drill to fix the error.

The Flash, in its final form, will head to San Diego this week, where it will stand on display Lego's Comic Con booth.

In years past, the toy company's produced large-scale models of Wonder Woman, Superman and Batman. The team built its first DC Comics model — the Dark Knight perched on a rooftop — back in 2005 ahead of the 2006 American International Toy Fair. The piece, designed by fellow Master Builder Erik Varszegi, is currently on display in the Enfield office's cafeteria.

Varszegi and Roe come from similar backgrounds— they actually attended art school together and started at the company just a year apart from one another. Though neither will attend this year's Comic Con, they've attended the conference in years past to see their work on display.

"I usually like to watch people look at it and see what they think," Roe said.

"That's probably one of the funnest parts," Varszegi added. "A lot of times when our models leave the shop, we never know where they end up. Last year we had the special thrill of being on site, and listening to people compliment them. They don't know the designers are right behind them. It gives you warm fuzzy feelings."