Plastic waste has been rapidly increasing in the past decades throughout the globe which creates a raising environmental concern. To manage this issue and prevent a nearby catastrophe, there had been a surfacing trend in utilizing plastic waste in additive manufacturing (3D printing). The focus of this paper is to upcycle High Density Polyethylene (HDPE), which is the second most commonly used plastic in the world. Several steps were done to transform the plastic waste into a filament for 3D printing. The working principle of achieving this was by manipulating the composition of the produced filament to match one of the more commonly used thermoplastics in 3D printing, Polylactic acid (PLA). This process was successfully executed by blending HDPE with low molecular weight Polypropylene (PP) and modified Polypropylene with Graft Maleic Anhydride (MAh) in a specified weight percentage (90%HDPE, 5% PP Mw-12, 000, 5% PP-MAh Mw-9, 100). Once a formula was obtained using virgin HDPE, we moved into utilizing plastic waste from shredded Laban bottles. Moreover, Tests like MFI, DSC, and tensile were performed to investigate the characteristics of the produced filaments and compare with commercially available alternatives.