This study investigates the effect of incorporating shredded E-glass fibers into polylactic acid (PLA) on the tensile strength, and flexural performance of honeycomb structures fabricated using fused deposition modeling. In addition, the study evaluates the relationship between fiber-reinforced composite materials and honeycomb cell-pitch geometry in determining the mechanical characteristics of the fabricated structures, while assessing the effectiveness of additive manufacturing in producing PLA-based composites. Composite filaments containing PLA and shredded E-glass fibers were manufactured through a twin-screw extrusion process using an 85:15 weight ratio, followed by the fabrication of honeycomb specimens via fused deposition modeling (FDM). Honeycomb structures with cell pitches of 3, 4, and 5 mm were prepared and evaluated through tensile and three-point bending tests in accordance with ASTM D638 and ASTM D790, respectively. The experimental results demonstrate that the shredded E-glass-reinforced PLA composite exhibited mechanical performance comparable to that of commercial PLA reinforced with carbon fiber. In particular, the honeycomb specimen with a 5 mm cell pitch achieved an ultimate tensile strength of 9.01 MPa, which was comparable to the 9.34 MPa obtained by the corresponding PLA/carbon fiber specimen. Furthermore, the 5 mm cell-pitch specimen reinforced with shredded E-glass exhibited superior flexural behavior, achieving a flexural strength of 42.83 MPa and a flexural modulus of 5.18 GPa. These findings demonstrate the potential of shredded E-glass-reinforced PLA manufactured by 3D printing as a composite material with potential cost advantages over carbon-fiber-reinforced PLA for lightweight semi-structural applications under quasi-static loading conditions.