Rotary 4D Printing of Programmable Metamaterials on Sustainable 4D Mandrel

Abstract This paper presents a novel rotary 4D printing platform capable of producing modular, multi‐material, multi‐stiffness cylindrical structures directly on a programmable, shape‐morphing mandrel. Inspired by bio‐inspired re‐entrant auxetic geometries, the design incorporates a parametric zigzag pathing strategy to dissipate stress and enhance resilience. The method supports non‐planar, continuous‐path toolpaths, overcoming the limitations of commercial slicers through a freely available open‐source rotary slicing algorithm. Comprehensive numerical and experimental studies to evaluate strain energy distribution, stiffness tunability, and 4D recovery in re‐entrant auxetic structures and spiral joints. A data‐driven predictive model is introduced to link geometric and material parameters to final shape‐morphing behavior, reducing dependence on iterative simulations. The integrated path‐planning approach significantly distributes localized Von Mises stress, particularly in hinge regions, while preserving global energy absorption. Using Python scripting within the Grasshopper environment, the complete design‐to‐G‐code algorithm is developed, enabling direct fabrication of non‐planar 4D structures, including multi‐spiral universal joints with programmable stiffness and multi‐degree‐of‐freedom motion. This work establishes a new paradigm in rotary 4D printing by uniting algorithmic design, stimuli‐responsive behavior, and reproducible fabrication within a single open framework. It is concluded by discussing broader implications for sustainable manufacturing, with potential applications in soft robotics, wearable systems, and deployable structures.