Additive manufacturing is one part of manufacturing engineering, the goal is to produce objects by applying particles in thin layers. In order to obtain the final product, it is necessary to construct a three-dimensional model with computer modeling programs or digitize an existing object. The goal of this work was to successfully produce a functional filament with a diameter of 1.75 mm that can be used to make reactor parts for the photocatalytic degradation of pollutants. The extruding mixture was prepared using the dry blending method by mixing low density polyethylene granules (PE-LD) with titanium dioxide (TiO2) and carbon nanotubes (CNT) in various proportions. The resulting mixture must first be extruded on a twin-screw extruder, followed by shredding and extrusion on a single-screw extruder. CNT was added up to 0,25 %, and TiO2 up to 15 % by mass. The obtained filament was characterized by differential scanning calorimetry (DSC), thermogravimetric method (TGA) and tensile test. The sample for the universal testing machine was designed in a computer-aided design (CAD) program and after design it was printed with a 3D-printer. Finally, the 3D-printing conditions were optimized based on the most successful printing of the sample that was suitable for the universal testing machine. As a result, three samples of each composite and three samples of pure PE-LD were successfully produced. Differential scanning calorimetry did not observe a proper trend of melting point change with the addition of fillers. By thermogravimetric analysis, it was established that the actual mass fraction of the filler in the sample is not equal to that mixed in, and that the addition of the filler increases the necessary temperature for the start of decomposition of the sample mass. The results obtained by the tensile test by testing on the universal testing machine do not show a trend of change in tensile strength with the addition of fillers.