HygroMetric: A Computational Framework for Hygromorphic Shape-Morphing

Designers have long relied on steam bending, lamination techniques, kerf cuts, and considerable craft to shape curved wood. What if wood could be programmed to shape itself beyond bending, making complex forms more affordable? We present a computational framework for 3D printing wood-based hygromorphic structures that morph from initially flat sheets into two distinct doubly curved, non-developable surfaces upon hydration and dehydration. Our tool supports both forward and inverse design: starting from primitives or a target geometry, it generates deposition toolpaths and predicts wet and dry states. We characterize anisotropic swelling and shrinkage to calibrate the simulator and evaluate accuracy via corresponding point-pair distances on simulated and printed forms. Finally, we present primitive-based designs and three application demonstrations using our framework. By coupling material behavior with design intent on consumer-grade printers, our framework reduces skill and equipment barriers and enables new fabrication and design possibilities in wood-based practice.