3D-printed Y-zipper turns from flexible to hard in less time than it takes to zip your fly

All zipped up

by · TechRadar

News By Lance Ulanoff published 5 May 2026

(Image credit: MIT)

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  • Y-zipper is a 3D-printed three-sized zipper
  • Is flexible when unzipped but rigid when zipped up
  • The 40-year-old concept was brought to light by researchers using software and a 3D printer

Let's make zippers interesting again. Right now, they're just part of your coat, pants, or fashionable bag, but what if a zipper could serve as the framework for a cast on your broken leg, or help you construct a tent in one minute? That's the kind of zipper we could all get behind, and apparently, it exists as something called Y-zipper.

Y-zipper is the real-world realization of a 40-year-old design dream. Forty years ago, former Polaroid engineer and current MIT professor William Freedman, PhD, envisioned a three-sided zipper. It would be like a traditional zipper in that it would have pieces that interlock to form a strong bond, but by adding a third side and zipping them together, it could create a potentially rigid structure that could be unzipped to return to a flexible form.

According to a report in MIT's News Journal, though, Dr. Freeman's design was rejected in 1985 by a prestigious design competition.

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In the intervening years, new materials and 3D printing arrived, making it possible to create an automated assembly and revive the Y-zipper idea.

A second chance for this innovative Y-zipper

Y-Zipper: 3D Printing Flexible-Rigid Transitions in One Click - YouTube

Watch On

In a project led by MIT postdoc and CSAIL researcher Jiaji Li, they created a 3D printable version of the Y-zipper. Each zipper begins as a design on the computer where Li and his team connect triangular and zippable primatives, bending and curving them however they want.

Once they have a Y-zipper's rigid design, they break it down into three printable flat zipper panels. Then they print them out, peel them off the print table, and use a custom-designed slider to weave them together. The three sections are each fed into one of three slots, and like the slider on your traditional zipper, as you pull the three pieces through this slider, they lock together and come out as a rigid shape on the other side. That shape can be a rod, a curve, or even a corkscrew (it all depends on how each side was printed and the angles contained within). When you move the pieces back through the slider or reverse the slider, the three pieces cascade apart as

It looks cool, but there are even sexier, more practical applications.

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