The flexural strengths of polymers are useful to determine their resistance to flexural deformation. The proposed study is the first of its kind to determine the impact of build orientations and temperature on the flexural strengths of PLA (Poly Lactic Acid) varieties and compare the results against PETG (Polyethylene Terephthalate Glycol). The main aim was to investigate the influence of the build orientations and heat treatment (HT) of the polymer samples on their flexural strengths individually and together (build orientation followed by HT procedures). The primary objective was to determine the flexural strengths of PLA, PLA+, PLA Pro+, and PETG by subjecting them to HT for 2 h and 3 h individually at 100 °C after printing them at two different orientations: F (Flat), and OE (On the Edge). The polymer samples were printed in on the edge (OE) and, flat (F), and were categorized into three types based on HT durations: No HT (HT_0), HT for 2 h (HT_2), and HT for 3 h (HT_3). The results of the flexural strength tests showed that PETG F_HT_2 and PLA OE_HT_2 exhibited the highest, and second-highest flexural strengths i.e. 255.78 (± 7.69) MPa (Mega Pascal), and 253.34 (± 7.04) MPa, respectively. The study demonstrated the influences of build orientations and HT individually and together on the flexural strengths of the polymers. In summary, the various flexural strengths of polymers offer special advantages in industrial robotics, orthotics, prosthetics, and implants by enabling material selection that suits specific application requirements.