InSituWear: On-body Fabrication of Custom-fit Wearable Structures using Melt-drawn PCL Filaments

We present InSituWear, a form-finding, on-body robotic fabrication method that melt-draws low-temperature thermoplastic polycaprolactone (PCL) directly onto the human body to create personalized wearables. Heated to a plasticized state, PCL is stretched into microfilaments (minimum diameter ≈ 0.03 mm) and robotically drawn in 3D; upon cooling, the filaments adhere and retain shape. Because PCL conforms around 50 ° C and cools rapidly, our process eliminates 3D capture, digital modeling, and assembly, enabling immediate, body-conforming wear at skin-safe temperatures. We present a tunable design system that varies filament diameter, wrapping density, and weaving pattern to locally control stiffness and compliance, improving comfort relative to sheet-based thermoplastics. Technical experimentation characterizes how fabrication parameters (speed, temperature, composition, and path strategy) affect performance. Finally, we demonstrate personalized body-wrapped wearables (e.g., sleeve, glove) and speculate on larger-scale applications (e.g., furniture, architectural surfaces) that showcase enhanced fit, waste-free fabrication, and intelligent behavior. These prototypes outline a framework for embodied, form-finding, adaptive robotic fabrication in HCI.