This study designed, produced, and validated 3D printing filaments based on polylactic acid (PLA) reinforced with pecan shell powder, with the aim of assessing their technical and functional feasibility as a sustainable biocomposite suitable for extrusion and 3D printing processes. Formulations containing 5 % and 10 % of agricultural residue were developed, controlling the particle size of the additive to prevent clogging during extrusion and ensure a homogeneous dispersion within the polymer matrix. The characterisation of the filaments included tensile and impact mechanical tests, as well as thermogravimetric analysis (TGA). Standardised specimens were fabricated via 3D printing to evaluate the material’s processability and the dimensional stability of the printed parts. The formulation containing 5 % pecan shell exhibited the best overall performance, showing increases of 18.2 % in Stress Peak, 8.7 % in Young’s Modulus, and 5.9 % in Impact Strength compared to pure PLA, as well as a slight improvement in thermal stability for the biocomposite. These findings confirm the technical feasibility of using pecan shell, an agricultural by-product native to the Peruvian context, as a natural additive in the manufacturing of biocomposite filaments. The research contributes to the revaluation of agro-industrial waste and to the development of more sustainable and cost-efficient additive manufacturing, proposing a functional biocomposite material with potential applications in the 3D printing of lightweight components, biodegradable packaging, and decorative parts with low to moderate mechanical requirements.