We Built a Paper-Folding Assembly Line…

I was up at 2:30 a.m. in the studio, folding boxes. I wanted to send a themed calendar to some fans—just a few hundred—but packing by hand would have taken a whole week. I kept thinking, what if a machine could fold these boxes automatically, so I could go home early and read a book? Good news: those machines exist. But we love DIY, so we decided to build our own small assembly line.

I couldn’t help but think what if there was a machine that could fold these boxes automatically?
This machine was our answer — a way to turn cheap paper into something meaningful.
When that first dove came out, it was the happiest moment of my year.

Building the box-folding line

A robotic arm grabs a sheet of cardboard, moves it forward and presses it down. Two side arms lock the sides in place. That part was straightforward; we took inspiration from existing designs. Most commercial machines, though, don’t close the lid, so we had to solve that ourselves.

Once the box is roughly folded, the platform moves it forward and another mechanism pushes the lid shut. The tricky bit was tucking a tiny flap into its slot. At first we pushed the lid down, but the flap bent outward and wouldn’t go in. We added a guide to nudge it inward, but small size variations still caused failures.

Our final fix was a spring-loaded guide on a movable air cylinder that adapts to each box size and gently pushes the flap in before the lid closes. The success rate jumped. But folding the box isn’t useful on its own—you still have to open it, put things inside, and close it again. So we added a robotic arm.

Now, once a box is folded it moves forward and the arm drops in a calendar and a wood block. The box is pushed along, the lid closes, and you have a fully packed box—completely automatic.

Scaling and the limits of shipping

You might ask, “Isn’t folding by hand faster than building all this?” Please don’t ask that question. Still, it looks pretty cool. The line can pack one box every 15 seconds, which is about 1,000 boxes in an afternoon. The bigger problem, though, was cost: calendars are expensive. Sending tens of thousands would be unaffordable, so we looked for something meaningful and cheap to send to everyone.

Assembly Line 2.0 — the paper-dove machine

Introducing Assembly Line 2.0: a paper-folding machine that turns a flat sheet into a paper dove, a symbol of sky, dream, and the ability to fly.

Step one is picking up a single sheet from a stack. That’s easy for humans but hard for suction cups, so we used a center-spinning wheel that pulls one sheet back, then forward into the rollers. Step two is folding: first in half, then into a boat shape, then pressing the tip down to create four crease lines. A robot arm picks up the paper and moves it to the next station, where steel blades on both sides fold along the creases and another blade folds a small corner.

The rough dove shape is formed by more folds. We fold the paper again, flip the wings down, and that’s where it gets complex. A robotic arm grabs the paper and feeds it into rollers. Rollers flatten it, then lift the wings. Molds press to make the creases. A third arm grips and pulls the paper further for final shaping. That step always gave me headaches.

The hardest part is the head and tail. Normally you’d pinch the paper by hand—very tricky even for humans. Our machine’s solution: the robotic arm places the paper down, then very fast the right mold punches down to form the head, the left mold punches the tail, and a cylinder clamps it all into shape. The piece swings to the end of the line. Boom—a paper dove is born.

We slowed down the rollers for the video so you can actually see the process. A blank dove felt incomplete, so we added a printing station at the start. Now we can print messages on each dove and included a little stand for a desk display. I wrote “new video” on mine as a reminder to hurry up. Our engineer wrote “99%” for machine accuracy. Our producer wrote “Ana de Armas” for reasons I still don’t understand.

Why we did this — and what happened next

I’ve always been shy. I rarely raised my hand in class. I’d rather use a vending machine than talk to a cashier. Watching videos alone at home became my comfort zone. In a weird way, people on screen felt more familiar than the ones around me. Then I started making videos, and I’ve been lucky to get a lot of support.

When our channel hit 10 million followers in China, I wanted to do a giveaway. But giveaways reach only a few lucky people. I wanted more people to feel my gratitude. This machine was our answer: a way to turn cheap paper into something meaningful. Why doves? Because I often delay posting videos—in Chinese it’s called “pigeon-ing” the upload. It became a meme about our channel, and we turned that meme into a real gift.

This was by far our hardest project. We started in April 2023. It took seven months to fold the first dove and two more months to make the machine reliable. Every step required countless tests, failures, and fixes. I doubted whether it was possible, but when that first dove came out, it was the happiest moment of my year.

We planned to send 100,000 paper doves folded by our machine in the studio. This video was posted in China in January 2024. Since then, we shipped 88,000 doves for free, and I’m really happy our viewers got to receive them. We’re now translating our videos for YouTube, and in just a few months we grew to 1,000,000 subscribers here. Thank you so much.

Hi, I’m Richard. We’re a DIY studio in China that makes weird stuff. Follow for more.