Yun Goo: The Creator Behind the Viral HelixCore Spinning Ball

Professionally, he designs stamping molds for products made by the millions. But what really made him famous was a small toy printed one piece at a time.

Pawel Slusarczyk | August 20, 2026

HelixCore – Press-to-Spin Squishy Ball 👈
On the day this article was published, this model had accumulated 22.3k downloads, 19.2k prints, and over 1,200 ratings on MakerWorld. No one in Malaysia, where Yun lives, recognizes him for this work; however, in China, where he is mainly known by his MakerWorld nickname “YY the panjang”, people stop him at events to ask for his autograph.

For the past 16 years, Yun Goo has been designing products that would be manufactured by the millions: injection molds, mass production, identical parts stamped out one after another. In this kind of work, success means the thousandth piece must look exactly like the first.

Yet, he has become known for the exact opposite: a toy made one piece at a time on a desktop 3D printer.

At first glance, it's an extremely simple thing: a ball that, when pressed, begins to spin. That's it.

Yun calls it HelixCore.

When asked why his models repeatedly break popularity records, he gives a surprisingly candid answer.

"If you ask me how to make these things go viral, honestly, I have no idea. It just happened."

But don't be fooled by that statement. There is no coincidence here... it is the result of years of manufacturing work and experience, which naturally evolved into creating outstanding works using 3D printers.

The Factory That Taught Him Everything

Before we talk about printing bananas, oranges, and spinning balls, we need to go back to the factory floor, because that's where the whole story begins.

Yun works in a family company founded by his uncle, who is still a director of the company. He joined the company partly by chance and partly out of necessity. He studied aircraft maintenance but never actually entered the aviation industry.

"My educational background is a bit strange. I studied aircraft maintenance, but I never got into aviation."

His father's death when Yun was young changed his life plans. He didn't want to spend years studying; he wanted to start earning money, so he joined his uncle's factory and learned the ropes from the inside out. He didn't start from a designer's desk or an existing position, but from the ground up, going through every step.

"Basically, I learned everything in this company. Every process, from polishing, machining, to laser welding. Every skill needed to make a mold, I learned."

It's worth pausing here because this is not an ordinary resume. Making injection molds is one of the most demanding jobs in manufacturing. Molds are the negative shape of a product machined from steel, with tolerances measured in hundredths of a millimeter, and they must withstand tens of thousands of cycles of hot plastic injected under pressure.

You don't just design the part itself, but also how the plastic flows into the mold, how it cools, how it shrinks, and how the finished product is ejected without damage. Yun has done it all: from product design, mold making, and production, all the way to production line automation and PLC programming; the complete chain, from the first drawing to a self-running machine.

As a result, his perspective on 3D printing is different from most people who start in this field.

Yun doesn't view a printer like an amateur who just discovered that layers can stick together and that the first layer must adhere to the print bed.

He sees it as someone who knows exactly how many steps, how much money, and how much responsibility lie between a beautiful drawing and a tangible object. This perspective will reappear many times in the story because it explains almost every decision he makes.

Ten Years, Three Self-Built Printers, and One Failure

Yun’s involvement with 3D printing goes back much further than his recent surge in popularity suggests—over 10 years. Like many of his generation, he started by ordering a DIY kit from Taobao.

The body was made of laser-cut polycarbonate sheets, and the heated bed was covered with ordinary painter's tape. It was a machine that required patience and the acceptance that a fair number of prints would look strange, or fail entirely.

This would deter most people, but Yun was captivated—so much so that he began to build his own machines from scratch.

The second one was more serious: an all-metal body, an Ultimaker-like frame, and a linear motion system based on MakerBot profiles.

The third was the most ambitious, and the craziest: around 2018, he built his own four-nozzle printer, at a time when multi-material printing was still only explored by a few enthusiasts.

Two nozzles worked; the other two never did.

The project stalled. Yun put it aside, and soon after, he put 3D printing aside entirely for several years.

Life went on, and the machine remained there.

This is an important moment in the story because it shows that his later success did not come from an easy start, but from a long period of trial and error: nothing earth-shattering happened, and some things simply failed.

He only returned last year. He returned because he kept hearing a name on everyone's lips.

"When I got back into 3D printing, I kept hearing this name: Bambu Lab. Everyone said it was a very good printer, a great machine. So I was curious and bought a P1S."

Compared to his self-built four-nozzle machine, the difference was fundamental: this was a machine that just printed, without needing you to fix it first. Yun started printing again, buying filament, making this and that. Then, almost naturally, he transitioned from printing other people's files to creating his own designs.

The Hours After the Kids Are Asleep

He started designing rather than just printing for a mundane, yet serious reason: money.

"At first it was just for fun. Then last year I ran into some financial difficulties and was trying to find a side income."

The situation left him little room: a full-time job at the factory, two children, and a house that only quieted down late at night. Free time only appeared in a narrow window after the children were asleep, just a few hours, no more. Whatever side hustle he wanted to do had to fit into this time without disrupting everything else.

He tried different things before finding what worked.

"I tested many things. I tried e-commerce, even selling insurance. But none of it worked for me. Then I found that this 3D printing design thing really suited me."

Design had an advantage that other ideas lacked: it accommodated his pace, not the other way around. It didn't demand constant availability at specific times, wasn't driven by client deadlines, and didn't require him to serve anyone instantly.

Moreover, it could bring in some income. Initially, that was enough for him to give it a serious try.

Why a Banana Must Open

Yun knew something most makers don't, but which changes everything about mass production: when it comes to volume, 3D printing cannot compete with injection molding.

At the scale of tens of thousands, hundreds of thousands, or a million units, injection molding will win on cost every time, by a huge margin.

Printing the same item on a 3D printer, each piece is slower and more expensive, and that won't change. For someone with his experience, this is not an opinion, but arithmetic. From this arithmetic, he drew a conclusion that became his method.

"3D printing cannot compete with injection molding. There's simply no competition in terms of quantity. So, when we create something for 3D printing, it must be unique. We can't do it the usual way."

For Yun, "unique" has a very specific engineering meaning: movement. Mechanisms hidden within an object. Something that comes alive in your hands.

This was already evident in his first model. The Banana Katana came about because his son wanted a toy, and Yun happened to have a newly bought printer and a reason to use it.

"I wasn't the first person to make this banana katana. But I printed one and thought, hey, I can add a little mechanism inside to make it different. So I added a mechanism, and when you twist it, the banana opens. The mechanical aspect is my strong suit."

Here, 16 years of mold-making experience became a real advantage. Designing moving parts requires exactly the same knowledge used when building molds: how components fit together, how much clearance to leave so that the object rotates without wobbling, how to choose tolerances so that it works correctly the first time.

On the factory floor, this knowledge is used to make injection molding machines produce identical, flawless parts; at Yun's desk, he uses it for something completely different—to give single prints a spark that mass-produced toys simply don't have.

An Orange, Some Lights, and a Spinning Ball

After the banana came the orange. More precisely, a citrus-themed stress toy designed before Chinese New Year, with a very personal origin.

"During Chinese New Year, we eat these citrus fruits in Malaysia. So I thought, why not make a stress toy that looks like a citrus fruit? And honestly, whenever I peel an orange, I always want to peel it in a certain way."

This little object contains a bit of Yun's own personality. He transformed an everyday action—peeling an orange in a specific, satisfying way—into a design.

This model garnered over 12,000 downloads, roughly similar to the banana model. At that moment, he felt he had found his direction: stress toys and fruits, movable, simple, familiar, and effective.

There were also failures along the way, such as the lights. Yun noticed that selling printed lamps could be very profitable, with a large gap between production cost and selling price, so he tried it, but it didn't succeed.

Then HelixCore appeared, and the scale changed dramatically.

As is Yun's usual practice, it started with an existing design. He printed several popular stress balls, the kind that click when squeezed and provide satisfaction. He liked them, but as always, felt they were incomplete: they lacked something he knew how to add better than anyone.

He sat down and designed a ball with an internal bearing and a screw mechanism. Press it, and it spins. A simple idea, precisely executed, exactly what he learned to do from his mold work.

During the creation of the model, something happened that even he couldn't quite explain, but many creators will recognize.

"When I was making that design, I had a feeling. It's hard to describe, but it was like something was pushing me from behind, telling me this might be the direction. It felt like something magical was about to happen."

His intuition was correct. Helix went further than any of his previous works: 22.3k downloads, 19.2k prints, and over 1,200 ratings on MakerWorld.

On Chinese TikTok, a video of the spinning ball accumulated approximately 400,000 views—and in the 3D printing community, this means that the vast majority of people involved in this hobby in China have likely seen it.

Unknown in Malaysia, Yet Recognized in China

At that point, the unexpected part began: being recognized. But not where he lived his daily life.

"In Malaysia, I'm still a nobody, just a regular person. But when I go to China, people recognize me. They ask for autographs, for photos together."

To be honest, it's worth clarifying: this refers to the 3D printing community, not street recognition. His videos were watched by hundreds of thousands of people involved in the technology, so when he appeared at industry exhibitions in China, people recognized him.

Outside the industry, he remains anonymous in China, and even more so in Malaysia; he picks up his children and buys groceries like everyone else. But for someone who, just a year ago, was only designing for himself at night, the mere fact that someone asked for his autograph must feel like a dream.

For him, posting on MakerWorld was not a matter of chance or vanity. Yun explains it like an engineer who understands that "a design without an audience doesn't really exist."

"No matter how good the design is, if no one sees it, it's still a failure. To go further, you have to put your work where others can find it. Otherwise, it just sits on your hard drive and goes nowhere."

He currently uses three Bambu Lab printers, and his choice of them once again reveals his engineering mindset. He started with a P1S, then bought an A1 for a very specific reason: comments started appearing on his models saying that the print profiles didn't work properly on the A1. Instead of ignoring or guessing, he specifically bought the machine to test it himself.

"Before I upload any print profile, I make sure it prints well and consistently on my own printer. Only then do I upload it to MakerWorld."

This is the same discipline that determines whether molds on the factory floor are ready for production. It's not enough for it to work once in your hands; it must work consistently, and it must work in the hands of people who have never seen it and don't know its weaknesses.

His third printer, an H2D, was exchanged for credits earned on MakerWorld itself, closing a loop in the process: the platform where he publishes his work effectively paid for the machine he uses to create his next batch of models.

He uses Fusion 360 for design, which is also a professional decision based on cost. Yun is familiar with more powerful and expensive engineering software from his day job, but his reason for choosing Fusion is simple: his license costs about 2,500 RM, while professional software can cost hundreds of thousands, and for what he needs to do, both offer very similar capabilities.

For someone who started due to financial problems, this is not a trivial difference.

It's worth taking a slightly broader view, as Yun has also witnessed how 3D printing has changed in his region. Malaysia is just beginning to adapt to this technology.

"When I started with 3D printing ten years ago, I couldn't find anyone else with the same interest."

Today, the Malaysian Facebook 3D printing group has 20,000 to 30,000 members. Relatively few people still own printers at home, and the overall user base is still small, but it's a huge leap compared to the days when Yun assembled printers from polycarbonate sheets. He himself is part of this change, and one of its more visible faces.

The Millions He Didn't Lose, and a Door He Wants to Open

A part of this story could easily be portrayed as unfair. Yun's take on it is completely different, and his attitude towards it is probably the most interesting aspect of the entire interview.

Helix began to be commercialized. Someone took his design and started producing physical toys for sale. At that time, Yun did not hold a patent for it.

"I kept hearing people in China say that I lost millions."

This statement doesn't align with his thoughts, and the reason why is worth specifying precisely, as it can be easily misinterpreted. Yun is not shrugging off others copying his work, nor is he saying that mass production without permission is fine. His view is narrower, and one that only someone who understands scale would have.

"Even if millions were sold, there's no way I could have produced and sold all those millions myself anyway."

After design, there's manufacturing, quality control, packaging, distribution, logistics, and one thing creators think about least—liability.

Including the heaviest kind of liability: the kind you only start thinking about when something goes wrong, like a child swallowing a piece from a poorly designed toy. To make a product succeed at that scale requires factories, e-commerce, distribution, and many other people.

So, he doesn't view every sold replica as money taken from his pocket. However, he still believes that original designers should be respected and properly compensated.

Crucially, the story doesn't stop at this realization. Since the HelixCore incident, Yun has started applying for patent protection and establishing a more formal licensing system around the design. He also found someone willing to support him—an investor who believed in the project and supported the IP aspect. Together, they have invested approximately 100,000 RMB in patent and IP protection.

"Honestly, when I first uploaded a small spinning ball to MakerWorld, I never thought I'd be doing these things, haha."

Even more interesting is how he now views patents. For most people, a patent is a wall, a way to stop others; Yun, however, is drawn to the opposite idea.

"I don't just want to use patents to stop others from copying; I also want to see if I can use them to open a door for other designers."

The vision is still taking shape, but the outlines are clear. If successful, other designers could develop their own ideas around the HelixCore mechanism with proper permission, and Yun could help connect excellent works with manufacturers and licensing partners. This stems directly from what he learned the hard way.

There are many talented designers who can create amazing things on 3D printers, but going from a printed model to a truly mass-produced product is a completely different world—this is the gap he personally crossed with Helix.

"So, maybe one day, I can make it a little easier for other independent designers to walk this path."

For someone who, just a year ago, was only designing for himself at night, this is a remarkable outcome. MakerWorld has brought him an income that fits the pace of life with two children and a full-time job—the very side income he had been looking for but couldn't find in e-commerce or insurance.

It has given him an audience on the other side of the world; people who print his designs in places he has never visited. It has given him the identity of a creator, which he never even considered a year ago. In his balance sheet, this is not a list of losses.

"It has changed my life."

Creation is never easy. When Yun's designs started circulating online through unauthorized resales, the MakerWorld team contacted him almost immediately. The platform views copyright protection as one of its core responsibilities to creators.

Dora Ding, Creator Relations & Operations Expert at MakerWorld, stated: "The moment we discovered infringement on this exclusive model, we contacted him directly and offered full support."

In practice, this meant assisting Yun in submitting takedown requests for infringing listings and stating that they would continue to take action against unauthorized websites, ensuring that creators' hard work receives the respect it deserves.

In his daily life, Yun still goes to work at his uncle's factory, still wearing his company uniform. He speaks of this with affection, because it is the flexibility of the family business that allows him to board a plane for another exhibition in China when invited.

He's already designing more fruits: bananas, oranges, and maybe one day a pineapple. He's also preparing a smaller version of Helix, this time without bearings, because users have started asking for it in the comments—and he listens.

When he tries to sum up what has happened to him in the past year in one sentence, it still sounds like he can't quite believe it himself.

"It's been a very wonderful experience. I would say, very wonderful. I never expected something like this to happen in my life."

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