"I felt so bad," Mr Kirkpatrick said.

"I watched that movie and then you have the great reveal that Lord Business is the kid's dad and he's glued the Lego together. I didn't glue the Lego, but once the set was made up, you don't break it up. We had piles of bits and pieces of Lego to play with."

Thankfully for Mr Kirkpatrick, when he called his now-grown eldest son to apologise, they both had the same view.

"My son said 'don't worry about it'. He said if it ends up in one huge box you can never make anything out of it."

Fellow Lego lover Bruce Abdilla agreed.

"I definitely have my Lego, and then Lego the nieces and nephews can play with," Mr Abdilla admitted.

"It tends to be the Lego that's easier to put back together."

Mr Abdilla and Mr Kirkpatrick are preparing to exhibit their wares at the Brick Expo in Canberra next weekend, where "well over a million dollars" worth of Lego will be on display.

While they love to put smiles on the faces of children who see their incredible constructions, it's more serious than just fun and games for the men.

Like the movie explains, Lego is much more than a child's toy.

"It's a highly sophisticate interlocking brick system", according Will Ferrell's character Lord Business.

The men said there is usually a transition time between when Lego stops being a toy and starts being a hobby. They call it "the dark ages", and not everyone reaches the light at the end of the tunnel.

"Virtually every adult fan of Lego goes through what's called the dark ages. Where maybe in the later teens where other things [take priority], they get distracted, which is fair enough," Mr Kirkpatrick said.

Only one of Mr Kirkpatrick's sons, now in their 20s, still enjoys looking at his creations.

"A proportion of them come back to it when they have children, then they realise they still enjoy it."

Mr Kirkpatrick didn't have that experience because growing up in New Zealand in the 1960s, he never had Lego.

"It was only when my kids in the 1980s and '90s were growing up that we started to buy it, and I bought far too much. I now collect classic Lego from that period.

"[The first set was] a swamp boat for my kids. I didn't think that much of it, but a few months later I discovered I was buying sets, and waiting for the kids to go to bed to make them up."

Mr Abdilla said as a child he loved playing with Lego, but he always wanted what he couldn't afford - trains. Now, he has one of the biggest train collections in the Canberra Lego Users Group.

After going through "the dark ages", he found the light when he was looking for a Christmas train to go around the tree for his own children.

One of the great things about the Brick Expo for Mr Abdilla is that he gets to run his trains along metres and metres of track - something he, and many other train enthusiasts - don't have the space for at home.

He hopes children that visit the expo will become the next generation of adult Lego enthusiasts.

"I just love that it's something simple you can get a lot of pleasure out of.

"You can play on the floor with a block and it can be whatever you want, your imagination is the biggest tool."

The Brick Expo not only entertains children, it also helps save lives by raising money for Paediatric Care at the Canberra Hospital (PatCH). Mr Abdilla said setting aside all the fun that's had at the expo, he's proud to raise money for a service that once saved his baby's life.

Born with a hole in her heart, his now 19-year-old daughter was cared for by PatCH.

"I wouldn't have my youngest daughter without them," he said.

The Brick Expo runs from Friday August 10 to Sunday August 12 at the Hellenic Club in Woden. Tickets for the Brick Expo are only available online. Visit this website for details, or buy tickets by clicking here.