How a ‘Y-Zipper’ Highlights the Potential of 3D-Printing

3D printing, or additive manufacturing, is often touted as the future of manufacturing. And in many ways, it already is, as it is getting deployed for advanced equipment like rocket nozzles, drone parts, or bespoke medical implants.

What makes 3D printing unique is its ability to create intricate shapes that would be very hard or even impossible to produce with traditional methods. In turn, this opens entirely new design possibilities.

So even if some traditional forms of manufacturing, like molding or machining, will likely stay around for basic parts, 3D printing is increasingly used to explore new ideas and revisit concepts that had been abandoned due to manufacturing complexity.

One recent such example is the “Y-zipper”, a concept originating from the 1980s, invented by a MIT professor. Similar in its basic principles to the usual flat zipper, the Y-zipper is three-sided and can adopt much more complex shapes.

The 40+ year-old patent has recently been revisited by researchers at the MIT CSAIL (Computer Science and Artificial Intelligence Laboratory), Tianjin University (China), Technical University of Munich (Germany), and Keio University (Japan).

Using modern 3D printing technology, they created and tested multiple versions of the Y-zipper and explored its potential application in medicine, robotics, and consumer goods. They published their findings at the Association for Computing Machinery (ACM)¹, under the title “Y-zipper: 3D Printing Flexible–Rigid Transition Mechanism for Rapid and Reversible Assembly”.

Zipper Explained

Zippers are made by assembling together two sets of perfectly identical plastic or metal teeth. A latching mechanism pushes the teeth to exactly the right angle to do so, and then can reverse the mechanism when pulled in the other direction.

It actually took almost 20 years for the concept to become a commercial success. This is because to be reliable and not ruin the bag, clothes, or other goods tied with the zipper, it needs to be manufactured with extreme precision so every tooth is perfect.

As a result, today’s market for zippers is dominated by one company, YKK, a Japanese firm that has built its dominance of this market over the high quality and reliability of its zippers, backed by total vertical integration.

Tunable Stiffness

A new class of material is looking to add to a material’s inherent properties extra flexibility, for example, moving from flexible to rigid, without changing the composition of the material.

Such rigid-to-flexible material transitions are a property sometimes referred to as tunable stiffness. Many methods have been explored to achieve this result, including inflatable structures, origami-inspired mechanisms, and Velcro-based assemblies. However, they all suffer from issues of durability, ease of manufacturing, or limited possible shapes.

Another approach is to use zippers that are stiff when zipped and flexible when unzipped. Some options have been developed, for example:

• StructCurves reconfigures zippers into block-like modules to increase closed-state stability,
• Touch-n-Curl introduces branched zipper topologies to stabilize complex, curved surfaces.

However, both methods use intricate tooth geometries that require manual, piece-by-piece assembly. This ultimately undermines one of the zipper’s core advantages: its rapid and reversible operation.

Another option, zip-chain actuators, stores a chain that becomes rigid when fed and locked.

These designs deliver rapid, reversible extension with high axial stiffness, yet require specialized hardware and tolerances, cannot be automatically adapted to different geometries, and are not printable all-in-one.

So the ideal method would require combining the traditional speed and reversability of a normal zipper with the tunable stiffness of zip-chain actuators, something that Y-zipper finally achieves.

Source: ACM

Y-Zipper Concept Explained

A 40-Year-Old Invention Back To Life

The concept of the Y-zipper was invented by William Freeman, forming a triangular shape, where on each side, he nailed a belt to connect narrow wooden “teeth” together. A slider wrapping around the device could be moved to straighten it into a triangular tube.

At the time, the concept drew little interest, but Freeman still patented his invention (patent #4,757,577).

Source: MIT

The opening or closing of the Y-zipper can be done manually, by pull-cord, or by robotic movement.

Manual movement is the simplest, helped by an undersurface grip on the slider. The pull cord can be activated by a fixed motor. Meanwhile, robotic/dynamic mechanical actuation used an N20 motor, microcontroller, a wireless receiver,  two additional custom 3D-printed gears, and a battery into a 15 mm × 25 mm × 35 mm package weighing only 18 g. The actuator could be wirelessly controlled via Bluetooth at distances up to 25 m.

Source: ACM

It can be scaled to extended lengths, up to 3 meters (10 feet), accommodating a wide range of form factors and applications.

The slider is made of the upper separator, which splits the strips when unzipping, and the lower converger, which joins them when zipping.

Source: ACM

The zipper’s stability comes from its three-way interlocking structure, allowing for smooth, rapid closure (at speeds of  30 cm/s). Unlike other zipper designs, the simpler teeth can move quickly and be manufactured quite easily.

“Compared to conventional zipper teeth, whose main function is to hold together the two sides of the thing being zipped up (such as the lid and body of a suitcase), the most critical role of the Y-zipper teeth is to provide sufficient structural support to the Y-zipper in the zipped up state.”

The bridges are the part that provides the structural integrity of the entire chain, or the “tensile-force-bearing unit”.

The ball nodes & sockets provide additional alignment during closure and primarily function to resist shear forces, preventing the zipper teeth from sliding against each other.

Source: ACM

How Can Y-Zipper Move?

In its simplest form, the Y-zipper can simply be formed into a stiff, triangular-shaped tube when assembled.

Another simple option is a bend arch, thanks to one of the strands having non-uniform teeth and curved bridges. The bending angle and effective bending radius can be fine-tuned through different tooth shapes and predicted by using a computer model.

Another option is to modify the inter-segment angles, creating a coil.

Source: ACM

Lastly, it can also be assembled in a screw shape, either in a clockwise or counterclockwise twist. The total screw angle can be varied as well, up to a point where the excessive angular mismatch between adjacent teeth occurs.

Source: ACM

Making Useful & Versatile Shapes

The straight and bent shapes are not mutually exclusive, and can be combined to create a large variety of shapes of the final zipped form. This means that the Y-zipper could ultimately be used to create an activable flexible structure of almost any shape, albeit not changeable once a design is fixed.

Source: ACM

A wide array of materials could be used for the Y-zipper. This could, of course, include wood, as in the original patent, but also flexible plastic like thermoplastic polyurethane (TPU), common 3D-printing plastics like polylactic acid (PLA), and even fabric, which could ultimately include materials like Kevlar fiber.

To create even more flexibility in potential designs, connections between different Y-zippers are needed. To this purpose, the researchers created a joint that can tie together up to three Y-zippers.

Source: ACM

Because the point Y-zipper is to be easily deployed when needed, compact storage is also a quality that users will look for in this product. So the researchers proposed a method to roll up the zipper for efficient storage, compacting a 0.5 m zipper (1.6 feet) into a cylindrical container with a height of only 10 cm (4 inches) and radius of 25mm (1 inch).

Source: ACM

Bringing The Y-Zipper To Real Life

Y-Zipper Applications

One of the most straight-to-market potential applications of the Y-zipper is medical braces, as 3D printing is already often used for similar applications.

For example, a wrist brace could be left in a flexible state during the day, allowing for free wrist movements, avoiding stiffness and muscle atrophy, and rigid during the patient’s sleep to avoid secondary injuries. The possibility of moving the zipper one-handed without assistance is an extra benefit.

Source: ACM

Another possibility is to create adjustable limbs for robots. In a simple prototype, the researchers created a robot that can rapidly adjust its height from 60 mm to 245 mm (2.3 – 9.6 inches) in under 3 seconds.

“Unlike traditional telescoping or multi-joint mechanisms, the Y-zipper achieves tunable leg length using only four lightweight tubes, without additional linkages or complex kinematics.”

Source: ACM

A third application can be the rapid assembly and disassembly of camping tents. The researchers created a frame consisting of four Y-zippers, a joint connecting them, and four corner anchors of the tent. The overall assembly time took about 1 minute and 20 seconds.

Source: ACM

Testing Limits

Of course, any real-world application will rely on the durability of the design. The researchers stress tested the design by running it continuously for 1 day and 15 hours, completing more than 18,000 cycles, one every 8 seconds, before a fracture finally occurred at the interface between the teeth and the bridges.

Overall, 18,000+ cycles, especially on early prototypes, prove that the design is already strong enough for most commercial use cases.

Stronger materials and computational methods to predict and compensate for gravitational sag could be deployed to improve the performance even further.

The accuracy of Y-zipper is limited by the 3D printing resolution. The narrowest functional strip width they achieved was 8 mm (0.3 inch). More advanced printing methods or future development of 3D printing could create even smaller Y-zippers.

In any case, the Y-zipper is one more example of the potential of 3D printing in not just replacing existing design and manufacturing methods, but opening the way for entirely new designs.

Investing In 3D Printing / Additive Manufacturing

Nano Dimension

Nano Dimension started with a focus on 3D-printed electronics. This position evolved when it successively acquired, in all-cash transactions in 2025, its competitors Desktop Metal and Markforged. This added many new materials, including high-tolerance metals, to the offer of the company, and helped it consolidate the 3D-printed electronic market.

This also created economies of scale by merging the customer base that includes SpaceX, Tesla, GE, Honeywell, Emerson, Raytheon, NASA, Medtronics, etc.

Lastly, the acquired companies were mostly active in different geographic areas, with Nano Dimension in Europe and Desktop Metal in the US, allowing for synergy by merging their sales teams.

Source: Nano Dimension

In 2026, Nano Dimension has been refocusing its product portfolio with the sale of 3D electronic printing technologies and its product line “Fabrica” to Inspira Technologies (IINN )

The resulting company will be focused on metal binder jetting (metal 3D printing), Software Platform, and Fused Filament Fabrication (FFF), and an overall shift from integration of its 2025’s M&A to scaling a unified technology platform across its global markets.

Investors need to be aware that the company has long been struggling to manage positive net income, in part because it has made acquisitions and invested in improving its technology.

In Q1 2026, Nano Dimension grew its revenues 106% year-to-year to $29.7M, and registered a $12.5M loss in adjusted EBITDA and $69.7M net loss. It held $441.6M in cash and other cash-equivalent liquid assets.

So the future of the company’s stock will be tied to its capacity to grow with the 3D printing industry as a whole and defend its position as a technology leader.

Latest Nano Dimension (NNDM) Stock News and Developments

Study Referenced

^{1. Jiaji Li, et al. Y-zipper: 3D Printing Flexible–Rigid Transition Mechanism for Rapid and Reversible Assembly. CHI ’26: Proceedings of the 2026 CHI Conference on Human Factors in Computing Systems. Article No.: 754, Pages 1 – 17. https://doi.org/10.1145/3772318.3790723}