The present work aims to evaluate the effects of varying the volume fraction of natural fibers reinforced in PLA on the mechanical properties of the resulting composites. The study involved preparing composite filaments by blending polylactic acid (PLA) with different percentages of pineapple and banana fiber particles, followed by 3D printing test samples using a Fused Deposition Modeling (FDM) printer. The results showed that increasing the volume fraction of Banana fibers up to 2% increased the compressive strength by 27.97% and flexural strength by 3.95% of the composite while decreasing its tensile strength by 5.6% compared to the plain PLA. With potential uses in the automotive, aerospace, and biomedical sectors, this study emphasizes the potential of pineapple and banana fiber powder as economical, sustainable reinforcements in 3D printed composites.