<p>This study aims to explore the impact of various infill patterns on the mechanical properties of 3D-printed polylactic acid (PLA) specimens, particularly focusing on the minimum cross-sectional area, which correlates with mechanical strength. A randomized controlled trial design was employed, testing four different infill patterns: concentric, gyroid, 3D honeycomb, and rays. Each pattern was printed in PLA using a standard material extrusion 3D printer. The specimens were subjected to tensile stress using a universal testing machine, following the ASTM D638-14 standard. The cross-sectional area at gauge length was calculated using the line-plane intersection method from GCODE analysis, highlighting the minimum cross-sectional area: the weakest sections theoretically prone to failure. This work involved testing specimens with varying infill patterns to determine their influence on the mechanical integrity and performance of the parts. The concentric infill pattern exhibited the highest relative line-plane intersection points (RLPI) and maintained minimal variability in mechanical properties across the sample size. Experimental results demonstrated that different infill patterns significantly affect tensile strength, with the concentric pattern providing the most favorable outcomes in terms of strength and reliability. The choice of infill pattern in material extrusion 3D printing of PLA significantly influences the mechanical properties, particularly the tensile strength and distribution of material within the cross-sectional area. The concentric pattern consistently outperformed other types in maintaining structural integrity under stress. These findings provide crucial insights for optimizing 3D printing settings to enhance the durability and performance of printed parts.</p>