3D-printing, in this case fused filament fabrication (FFF), shows potential as a versatile method to print simple electronic circuits attractive for the development of wearable devices, such as sensors and energy harvesting. We present the development of a nanocomposite - carbon nanotubes (CNT) in a polypropylene (PP) matrix - suitable for FFF. Both, short multi walled (MWNT), single walled (SWNT) and double walled (DWNT) nanotubes were evaluated. Firstly, masterbatches with up to 33 wt% CNT in the polymer matrix were produced via solution processing using a low Mw PP. The result was a porous structure of CNTs wrapped by the polymer, as observed by SEM. The highest resulting electrical conductivity c for our 33% composites was observed for the MWNT-masterbatch; cMWNT = 11.4 S/cm. This material was diluted by melt-mixing with an extrusion grade PP, with the aim to extrude the nanocomposite into a filament and finally print it using a commercial FFF printer.