Methods for producing 3D printing composite polymer materials for use in additive manufacturing processes are provided. The methods result in enhancing the material properties of the printing material by providing a uniform and smooth surface finish of the printing material and the nozzle extrudate for additive manufacturing processes, such as Fused Filament Fabrication. The method includes implementing impregnation techniques for combining carbon nanotubes or other nano-fillers, a polymer resin and a fiber material to produce a polymer material that can be processed into a printing material. Further, the method may include combining the carbon nanotubes or other nano-fillers and the polymer resin to form a masterbatch that may be further combined with the fiber material through an extrusion process. The method results in a printing material with enhanced material properties and smooth surface finish for the printing material and resulting nozzle extrudate for Fused Filament Fabrication.