Lego means different things to different people. To kids, it’s something you have to do when the PlayStation’s been confiscated. To parents, it’s why you never walk barefoot in the playroom. And to Nathan Sawaya, it’s art.

His exhibition, “The Art of the Brick,” has just returned to London after it first took the capital by storm a decade ago. The show — on Brick Lane, of course — now features 100 of Sawaya’s works created from more than a million pieces of Lego.

There’s a mirrored room full of Lego skulls. There are brick recreations of Klimt’s Kiss, Munch’s Scream and Michelangelo’s ceiling. There are life-size brick bodies — most famously Yellow, a self-portrait with chest torn open, brick guts spilling out — and there’s a crowd-pleasing 80,020-piece Tyrannosaurus rex.

Edvard Munch’s The Scream gains extra dimension in Nathan Sawaya’s Lego re-creation.

Sawaya, 50, built the dinosaur in New York over three hot months in 2007, a piece that stretched from the front of his apartment to the back. He was not married at the time. The T. rex now on show in London is the original but “The Art of the Brick” has become a global juggernaut, currently showing in Philadelphia, Paris and Miami as well. A million people will see a version of it this year alone, though the tickets are not cheap — from $17 for a child (4-12) and $25 for an adult.

“Yes, I’ve done duplicates,” he says. “I’ve made five T. rexes.” Five! He is now married and lives in Las Vegas with his wife, Courtney Brown, a publicity director at Amazon Studios, but his Lego has moved out. He has 10 million bricks in two studios and the Lego factory in Billund, Denmark, on speed dial.

The story of how Sawaya became one of the world’s most successful and well-remunerated artists is also a lesson on the importance of boredom. As a child growing up in a remote Oregon timber town in the 1980s, Sawaya was frequently bored, as children should be. “It was a very rural environment where the nearest friends were more than a mile away,” he says. “Lego became a thing I could focus on. I had endless new toys as long as I had the imagination to create them.”

He has 10 million bricks in two studios.

You don’t have to follow the instructions: that epiphany came when he was ten years old. He broke up the Lego city he’d built by the book and created a boat instead. Then a plane. Then a fort. Then, because his parents wouldn’t let him get a dog, he built one and took it for walks in the forest.

I tell him I also filled long school holidays building Lego “off book” and I tried to get my children to do the same but it’s harder today, with Ninjago and Star Wars and Technic. Every set and every piece is specialized. You can’t build a boat out of a dragon temple. Lego has become too prescriptive.

“I think the sets are a great doorway into using Lego, especially for younger kids,” says Sawaya. “They can follow the instructions and be proud of what they’ve created — but then they can tear it apart and build something new.” Mine didn’t, I tell him, and he says his own children never got the Lego bug either.

Sawaya was in his twenties when he returned to his childhood passion as a way to relax after stressful days at his Wall Street law firm. “I had Lego in my apartment but it was kind of hidden, because if I brought a woman over, I worried how she’d react,” he says. “I was seeing someone and every time we’d come back to the apartment, the doorman would hand me a package and I’d quickly put it away in the closet. She just didn’t understand. She thought I was either dealing drugs or I had some sort of horrible porn habit. When I finally admitted I was making art out of Lego, she was relieved.”

One of Sawaya’s life-size brick bodies, Yellow, a self-portrait, which is currently on display in London.

In 2004, after a Web site he put together to show his work crashed from the amount of interest, Sawaya handed in his notice to his bosses. They were puzzled. “Some colleagues were very supportive,” he says. “Others were much more negative. They thought I was crazy. A law firm can feel a bit like a prison and you’re all stuck there together. When someone escapes and you’re left behind, perhaps you get upset.”

Nobody thinks he’s crazy now. His larger works sell in swanky fine-art galleries for hundreds of thousands of dollars and he’s “doing the thing that makes me happy”. The new exhibition, which opened in early March, also has a missionary zeal to it. “Sometimes when you’re looking for a step up, you don’t have to look any further than yourself,” reads the note beside a yellow-brick man with a ladder for arms. “Love outlives youth and a flat stomach and a full head of hair,” it says beside a sagging red-brick couple holding hands. “That’s what makes it beautiful.” It’s life-coaching as Lego as art.

“I had Lego in my apartment but it was kind of hidden, because if I brought a woman over, I worried how she’d react.”

Sawaya even has a mantra, “Art is not optional”, and when I ask him to expand he tells me we all need a bit more creativity in our lives. “There’s definitely a correlation when it comes to kids and art. Students get higher grades when there’s art in the curriculum. Creating art makes you happier, healthier and smarter, so I want to encourage everyone to create a little art.”

At the end of the exhibition, there’s a play area full of bricks. Some children — but more adults — are busy creating a little art. Mission accomplished. But in the gift shop, they’re flogging sets. I have a flashback to the 3,803-piece Death Star it took five days for me and the kids (but mainly me) to complete. It hadn’t felt creative at the time. It hadn’t felt relaxing, either. I ask Sawaya what he does to relax now that Lego is the day job.

“I like to cook,” he says. “If I didn’t do this, I’d try to be a chef.”

On the Lego Web site they have all the sets, but Sawaya is an inspiring guy. I ignore the Minecraft section, the Avengers and the almost $500 Lego Lamborghini. I’m going to see what our ten-year-old can create with 1,000 plain bricks and no instructions.

“The Art of the Brick” is on at the Boiler House, in London, until May 19

Matt Rudd is a U.K.-based contributing editor at The Sunday Times and the author of Man Down: Why Men Are Unhappy and What We Can Do About It