This chapter explores the innovative use of fish scale waste as a reinforcing material in 3D printing applications to enhance the mechanical properties of polylactic acid (PLA) components, thus contributing to sustainable manufacturing practices. As the demand for environmentally friendly 3D printing materials increases, the integration of biodegradable PLA with naturally sourced fish scales presents a promising solution to reduce plastic waste and utilize bio-based composites. The narrative begins by detailing the composition and structural advantages of fish scales, highlighting their high collagen and mineral content, which can significantly improve the strength and durability of PLA-based products. It discusses the process of converting fish scales into fine powder and their subsequent incorporation into PLA filaments, outlining the specific ratios and techniques used in composite preparation. Subsequent sections evaluate the mechanical performance of the resulting fish scale-PLA composites, including tensile strength, flexibility, and impact resistance, through various testing methodologies. Comparative analyses with conventional PLA materials are provided to underscore the enhancements made by the addition of fish scale powder. Finally, the chapter addresses the environmental impact and economic feasibility of using fish scale waste in 3D printing, including potential market applications and sustainability benefits. This examination aims to provide valuable insights for manufacturers, researchers, and policymakers interested in advancing green technology in additive manufacturing.