Today, technological advances have led to the discovery of newly developed manufacturing methods. Additive Manufacturing technology with three-dimensional (3D) printer is one of these new methods. In this method, parts with complex geometry that cannot be produced by conventional methods can be manufactured. The most popular and low-priced method among additive manufacturing technologies is FDM (Fused Deposition Modeling). In this study, 3D printer design and manufacturing using FDM technology has been realized. Five different infill geometries such as hourglass (HG), gyroid (GY), octahedral (OC), triangle (TR) and grid (GR) have been determined, then the tensile and 3-point bending tests were applied to the manufactured Polylactic Acid polymer (PLA) samples and mechanical properties were compared with each other. The most important aspect of the study is the comparison of grid infill geometry, which has been studied extensively in the literature, and the rarely studied geometries such as hourglass, gyroid, octahedral and triangle in terms of mechanical properties. It was concluded that the different cross-section type has a significant effect, especially on tensile strength. The highest strength values were determined in the samples with triangular infill geometry.