Eighteen months ago, Jason Miller was toiling in a Lego retail store, and no one in the LegoLand theme-park universe knew his name. Today, he’s the master model builder for LegoLand Florida, the newest and largest of the LegoLand parks, opening Oct. 15 in Winter Haven, Florida.

Miller’s meteoric rise to the top of the brick-building business is the stuff of Lego-geek fantasy. Bummed out after ending a nine-year stint working in Orlando theme parks, Miller was in a career funk. His wife suggested shopping for a Lego set to cheer him up, knowing that he parted with all of his sets when he left for college. The pilgrimage to the Lego store reignited his childhood passion, and he applied for a job there. Miller worked as a cashier, stocker and store-display builder, but his leap from Lego peddler to theme-park builder came out of sheer chutzpah. On vacation at California’s LegoLand Park in 2010, he ambushed an employee, smartphone at the ready, and showed off some of his Lego creations.

“I had a video of a contraption I had made with a Lego motor and conveyor belt of Yoda chasing Darth Vader into a cave,” he said. “[The employee] liked it and forwarded it to his boss, and soon they were asking me to fly back to California for an interview.”

Ten months later, this past February, Miller landed in Winter Haven for his first day on the job as one of the park’s master model builder.

He presides over a hangar-like building lined with yellow bins filled with millions of bricks, but the job is more than just making models. Sending his one-ton babies—giant buildings and sculptures made of hundreds of thousands of bricks—out into the world can be as much of a challenge as creating them.

“Grand Central Station must have weighed 1,500 lbs., and it had to be lowered with an extendable boom into a concrete base where a spot had been cut for it,” he said. “It was nerve-wracking,”

When the park is completed, his role will shift from building and installing to maintenance mode, repairing models and replacing things that go missing.

Currently, Miller is “running on energy drinks” and relishing the thought of the crowd’s reaction on opening day.

“I’ve seen the park being built around me,” he said. “It’s been amazing to see everything come together.”