Polyethylene terephthalate glycol printed utilizing layers of extruded beads and Fused Deposition modeling by varying a key infill speed parameter (40, 50, and 60 mm/s, respectively) while maintaining ideal values for the remaining parameters. The overall performance depends on the annealing conditions and the infill speed. Mechanical characteristics like impact strength, tensile strength, and hardness are enhanced when 40 mm/s infill speed PETG samples are utilized. An appropriate annealing post-processing method enhanced interlayer diffusion bonding and improved mechanical properties in comparison with the as-built sample. The results are helpful guidelines for fabricating functional parts out of PETG, assuming a 40 mm/s infill speed during annealing. This was a nearly crucial aspect in the eventual replacement of structural metallic parts used in automobiles and aircraft.