Fused Deposition Modeling (FDM) is one of the most commonly used 3D printing technologies for creating complex parts from a Computer Aided Design (CAD) model. It is observed that mechanical strength of 3D printed polylactic acid (PLA) parts are affected by various parameters associated with part, process, material and operating conditions. One of the key parameters that influences tensile and flexural strength of 3D printed PLA parts is build orientation. Researchers have investigated the effect of a limited number of build orientations on tensile strength. Moreover, less work has been reported which studies the effect of build orientation on flexural strength. None of the studies modeled tensile load and bending load as a function of thickness and compared tensile loading capacity with flexural loading for different orientations. Therefore, an attempt is made to include a greater number of build orientations that occur during 3D printing of complex PLA parts. Build orientations considered in this study are flat, flat-support, edge, edge-45, upright and upright-45 with three thicknesses i.e., 1.2 mm, 2.0 mm and 2.8 mm. Tensile and flexural tests are performed as per American Society for Testing and Materials (ASTM) standards. Experimental results show that six orientations form two groups i.e., strong orientation group and weak orientation group. PLA appears stronger in tensile loading than bending. Edge orientation is strongest during tensile as well as bending loading whereas upright orientation is weakest in tensile loading and upright-45 orientation is weakest in bending. Force trends, it can be concluded that thickness can be minimized where build orientation belongs to the strong orientation group. Similarly, thickness can be increased where build orientation belongs to the weak orientation group.