Natural fiber filaments transforming the future of sustainable 3D printing.

The rapid advancement of additive manufacturing (AM), or 3D printing, has created unparalleled prospects for design innovation and production efficiency. Nonetheless, dependence on petroleum-derived polymers presents considerable environmental and sustainability issues. In reaction to these issues, natural fiber-reinforced filament technologies have surfaced as a promising approach for sustainable production. This review aims to objectively evaluate the progress in the development of natural fiber-reinforced filaments, emphasizing their capacity to diminish the carbon footprint of additive manufacturing while improving mechanical, thermal, and functional characteristics. This paper systematically examines manufacturing methodologies, including pelletization and extrusion processes, material behavior such as viscoelasticity and morphological characteristics, and assesses their performance in various applications within the automotive, aerospace, medical, and consumer goods sectors. Particular attention is directed on resolving enduring challenges including material inconsistency, moisture sensitivity, and recycling constraints. Moreover, the analysis delineates existing research deficiencies and suggests prospective avenues, including the incorporation of smart materials and the implementation of circular economy frameworks. This article provides a thorough assessment of difficulties and opportunities to facilitate the progress and practical implementation of sustainable natural fiber-based filaments in the next generation of additive manufacturing.