Challenges and innovations in sustainable 3D printing

Additive manufacturing (AM), or 3D printing, is a transformative production technology offering design freedom, material efficiency, and mass customization. However, its environmental sustainability remains a critical concern due to energy-intensive processes, limited recyclability of materials, and challenges in lifecycle impact assessment. This review presents a comprehensive analysis of sustainability challenges and innovations in AM, with a focus on material extrusion (MEX) and related polymer-based techniques. It explores the environmental performance of both virgin and recycled materials, the trade-offs between energy consumption and mechanical performance, and recent developments in biodegradable and bio-based polymers. The review also synthesizes findings from lifecycle assessments (LCAs), energy optimization experiments, and material circularity studies to provide an integrated framework for sustainable additive manufacturing. By bridging technological advances, material science, and sustainability metrics, this work highlights key strategies for aligning AM practices with circular economy principles. The review aims to guide researchers, engineers, and policymakers in understanding the current limitations and future directions of sustainable 3D printing.