3D printing holds strong potential for the formation of a new class of multifunctional nanocomposites. Therefore, both the nanocomposites and 3D printing communities need to make more collaborations and innovations for developing and processing of new polymers and composites to get benefit of functionalities of 3D printed nanocomposites. The contribution of this paper is the creation of 3D printable filaments from conductive polymer nanocomposites using a melt mixing process. Multi-walled carbon nanotubes (MWNT) and high-structured carbon black (Ketjenblack) (KB) were incorporated into polylactic acid. The percolation threshold of MWNT composites is 0.54 wt.% and of KB composites is 1.7 wt.% by four-point resistance measurement method. In the similar melt mixing process, there was no dependence of diameter of produced 3D printer filaments on the MWNT loading, instead the diameter was dependent on the KB loading and increased with increasing the filler amount. The conductivity of extruded filaments from 3D printer in low filler contents decreases with increasing extruder temperature, yet in higher filler contents there is no effect of extruder temperature on conductivity. Finally, the resistance decreases exponentially with the increase of cross sectional area of 3D printed tracks.