WillowMetric investigates the design and optimisation of a woven willow façade using parametric modelling in Rhino and Grasshopper. Through iterative analysis of pattern density, material distribution, and façade performance, the weaving system was refined to balance structural efficiency, shading, transparency, and aesthetic quality. The project demonstrates how computational design tools can inform material placement and fabrication strategies, transforming a traditional weaving technique into a responsive architectural façade that enhances environmental performance while maintaining a strong connection to natural materials and craft traditions.