Researchers at MIT have found a way to transform a flat sheet into a functional 3D object with a single pull of a string. It’s like a pop-up book, but way more complicated. And yet, it is somehow just as simplistic in execution.
The work comes from MIT’s Computer Science and Artificial Intelligence Laboratory and is detailed in a recent paper in ACM Transactions on Graphics. The project took inspiration from kirigami. Where origami is the Japanese art of folding paper, kirigami is the Japanese art of cutting paper to create complex shapes.
You know when you fold a paper a bunch, make a bunch of cuts, and then unfold it to create a snowflake shape? That’s kirigami.
This Pull-String Material Transforms Flat Sheets Into Structures on Demand
The team developed a computational method that lets users design three-dimensional objects that can be fabricated as flat grids and then deployed almost instantly with a single tug. Pretty neat, right?
You would never guess that the material does something that remarkable at first glance. It isn’t exciting to look at. It’s a tiled pattern of quadrilateral shapes arranged in a grid, flattened into a single sheet of tiles.
Embedded in that grid is an auxetic mechanism, meaning the structure behaves in counterintuitive ways. It gets thicker when stretched and thinner when compressed. This property allows the flat sheet to expand and lock into shape under tension.
The real innovation here is the algorithm behind it all. Users input a desired 3D shape, and the system translates it into a flat pattern to determine where cuts should go and how the tiles should be connected to achieve that shape.
Then it calculates an “optimal string path” that threads a single piece of string through the structure in exactly the way needed to create the intended shape when tugged. That string minimizes friction and evenly distributes force, so when you pull the string once, all tension is correctly applied to the areas the algorithm deemed necessary to create the shape you wanted.
There are no motors, hinges, or complex assembly instructions necessary here. This is simplicity at its finest. The entire system relies on a single smooth motion, a single tug of a string. That simplicity opens the door to practical uses where speed, portability, and ease of deployment matter most.
The team built real-world objects, including medical devices such as splints and posture supports, as well as dome-like shelters. Maybe the most remarkable thing they made was a human-sized chair using laser-cut plywood boxes.
When stretched out into a flat sheet, it may look like just a bunch of square logs standing side by side. When the string running throughout it was tugged, it deployed a chair that could support a person’s weight.
Scalability is an issue, though if that ever gets worked out, the long-term vision is to use this technology to create deployable medical tools, maybe even foldable robots or, if we’re really getting lofty here, modular habitats for space exploration that could be deployed at the pull of a cord.