<p>Recycled polyethylene terephthalate filament (R-PET) and recycled polypropylene filament (R-iPP) were successfully obtained from a recycling device called <i>Polyformer</i> which were reinforced with graphene oxide (GO) by dip-coating technique for use in 3D printing. The filaments were characterized by Differential Scanning Calorimetry (DSC) to obtain the main thermal transitions of the composite, such as its glass transition temperature (<i>T</i>_g), melting, and crystallization temperature (<i>T</i>_m and <i>T</i>_c, respectively). The specimens were printed according to ASTM D4065 standard and were characterized by dynamic mechanical analysis (DMA) to observe the impact of graphene oxide as reinforcement on the storage modulus of the material. The thermomechanical results indicate enhanced performance of the iPP-G composite, exhibiting a 21% increase in storage modulus and a shift in the glass transition temperature (<i>T</i>_g), indicative of effective interfacial bonding between the graphene oxide and the recycled iPP matrix.</p> Graphical abstract <p>Reinforcement of recycled commodity polymers for 3D printing</p>