Printer Wonderland: the game-changing technology that just arrived on the LEGO® Holiday Express

The LEGO® Icons Holiday Express Train (10361) is a festive set full of surprises, from the engine’s chugging smokestack to the bell-ringing polar bear surrounded by colourful gifts, which are neat callbacks to much-loved LEGO® sets of yesteryear.

But one element is a genuine piece of LEGO history: not the Holiday Express train itself, but the miniature blue train that comes with the set – the first 3D-printed piece ever to be included in a retail LEGO product.

“It’s a milestone,” said Ronen Hadar, the Head of Additive Design and Manufacturing at the LEGO Group. “This feels like a move similar in magnitude to when our founders purchased their first injection moulding machine back in the late 1940s!”

For the past nine years, Ronen and his team in Billund have been working to develop a 3D printing, or additive manufacturing, system capable of mass-producing high-quality LEGO elements. Low-rate 3D printing technology is already well established; LEGO designers have been using 3D printers to make prototype bricks in the lab for over a decade. But it can take hours to make a single piece.

Rapid industrial-scale printing, on the other hand, wasn’t yet established, and the team effectively had to invent the process from scratch, Ronen said.

LEGO bricks are produced by injection moulding, which is the best way to produce high-quality plastic parts in large volumes. The idea behind the 3D printing project was never to replace this tried-and-tested process, Ronen stressed. Rather, it unlocks new possibilities for LEGO elements in terms of form and function, creating ways of playing that LEGO sets couldn’t otherwise incorporate.

“We can make all kinds of geometries that are not possible with injection moulding,” Ronen said, “bricks with internal mechanisms for example.”

The miniature train aboard the LEGO Icons Holiday Express Train – which went on sale in October – is a sneak peek into this dynamic future. Besides its intricate shape, which mirrors that of the set’s larger locomotive, it comes with moving parts: wheels that spin and a puffing chimney.

“It’s a great way to showcase what we can do,” said Ronen.

Departing platform 3D

After years spent honing the technology, the question was when to deploy it in a real-life set that LEGO fans could enjoy.

“It could have been many things,” said Bo Park Kristensen, the designer of the miniature train element. “But in the end, we decided that this train would be the first mass-produced 3D print in a LEGO box.”

For the LEGO Icons Holiday Express Train set designer Jae Won Lee, the 3D printed train was the perfect way to add an extra dimension to the new set, which was itself an update on the LEGO Creator Expert Winter Holiday Train (set 10254) from 2016. Two child minifigures from that earlier set now feature in the Holiday Express as grown-ups delivering toys to a new generation of kids, and the design team, curious about the potential of 3D printing and eager to try it out, realized that these small toys could be an opportunity to create that first printed element, said Jae.

After Jae had designed the main brick-built train for the Holiday Express, he worked with Bo to perfect the miniature’s shape and ensure that one would be a micro replica of the other. Meanwhile, Ronen and his team was on hand to explain how far the technology could go in helping them to realize their ideas.

It was thrilling for the Additive Design and Manufacturing team to finally open up their technology to the designers, Ronen recalled. “This was so exciting for us: we’re additive manufacturing experts but they’re designers and they have that creative power to really apply the technology outside of what we thought was possible,” he said.

Next stop: brilliantly boring

Though just one feature of the Holiday Express Train, the miniature train adds a dimension of play that could not have been delivered using traditional production techniques. It has demonstrated the additive manufacturing system’s potential to the LEGO Group’s design teams, who are now looking at creative ways to harness the technology and incorporate similar dynamic touches into upcoming sets, said Ronen.

The additive manufacturing team is meanwhile focused on improving the LEGO Group’s additive manufacturing capability. They have already managed to double the output rate of their printing machines, according to Ronen, and are targeting further enhancements.

Ultimately, the goal is to transform the 3D element from a novelty or an added extra into an element that sits at the heart of the LEGO System.

“We still need to learn more about how to apply the technology, and where to apply it,” Ronen said. But the long-term goal is for the printed brick to be a standard feature of the LEGO designer’s toolkit.

“My task is to make 3D printed LEGO elements boring,” Ronen concluded, “so people don’t think about how it was manufactured, they just think it’s a cool element that gives them something fun to play with.”