MIT CSAIL has built a 3D-printable three-armed fastener that converts flexible plastic strips into rigid structures in seconds. Associate professor Stefanie Mueller's team revived a 1980s patent by MIT professor William Freeman, PhD '92, who originally designed a three-sided zipper that never reached production. Their custom software lets users configure strip length, bend angle, and final shape before printing.
The numbers are concrete. A tent using the fastener assembles in 80 seconds. A wrist cast built with it can be tightened or loosened on demand. Attach a motor and the structure becomes actuated, changing shape on command, which is how they demonstrated adjustable robot leg heights. The zipped result can be straight, bent, coiled, or twisted depending on how the strips are configured before printing.
The full paper is worth reading for the design software itself, not just the applications. The team had to solve how to reliably predict real-world rigidity from a digital configuration, and postdoc Jiaji Li's account of that process is the technical core the summary glosses over. The leap from Freeman's abandoned prototype to a programmable fabrication pipeline took four decades and a specific set of computational constraints to make work.
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