Lightweight Electromagnetic Wave‐Absorbing Metastructures: Advances in 3D Printing‐Based Design and Manufacturing

3D‐printed electromagnetic metastructures have revolutionized the design of lightweight, broadband electromagnetic wave absorbers through advanced control of wave impedance, scattering mechanisms, and multifunctional integration. Despite their potential for stealth technology, electromagnetic shielding, and microwave absorption, challenges remain in design methodology, material optimization, and scalable fabrication. This review systematically categorizes metastructure design into three approaches: 3D design, gradient impedance design, and bio‐inspired topology design, emphasizing their impact on absorption performance. Additive manufacturing techniques, including polymer‐ and ceramic‐based fabrication with hierarchical structural control, are analyzed for enhancing absorption efficiency and mechanical robustness. Key loss mechanisms “dielectric, magnetic losses, and structural resonance” are discussed to explain performance fundamentals. Critical challenges include balancing broadband absorption with mechanical strength, extending tunable frequency ranges, and scaling production for industrial applications. Future research should prioritize AI‐driven inverse design, multi‐functional material integration, and rapid multi‐scale manufacturing. The integration of machine learning and advanced 3D printing is poised to enable next‐generation high‐performance electromagnetic wave control materials. This review provides a roadmap for bridging fundamental research and practical applications in metastructure development.