Regulation Strategies for Extruded Filament in Material Extrusion Additive Manufacturing: A Review and Perspective

ABSTRACT Material extrusion (ME) additive manufacturing is widely employed for fabricating complex structures owing to its broad material compatibility and high design freedom. However, it is constrained by bottlenecks such as poor printing quality, significant anisotropy, and limited functionality, stemming from insufficient control over the extruded filament. This review establishes extruded filament as the fundamental regulatory unit, proposing an innovative framework for optimization centered on extruded filament. It systematically examines three primary categories of extruded filament regulation strategies—filler modification, shape control, and multimaterial printing—analyzed through the lenses of material properties, macroscopic morphology, and compositional complexity. By modularizing these strategies, this review elucidates their key characteristics and limitations, and clarifies the synergistic and conflicting interactions among them, thereby establishing a multi‐strategy integrated design framework. Building on this framework, critical breakthrough directions are identified to address current constraints. Future opportunities are further outlined, including cross‐disciplinary technology transfer, bioinspired design approaches, and green additive manufacturing enabled by material recycling. Collectively, these directions are expected to expand the design and application space of ME, enabling high‐performance, multifunctional additive manufacturing.