This diploma thesis covers the literature in the field of additive manufacturing using selective laser melting – SLM. Milling is introduced, as a post-processing technology, which is crucial to ensure required surface roughness and high dimensional accuracy of 3D printed parts. In the thesis, both technologies are analyzed and applied in the production of a conformal cooled injection mould core. Due to the specific nature of SLM technology, the cooling ducts have uneven roughness; therefore, abrasive flow machining – AFM and chemical polishing technologies are used afterwards. 3D printing, post-processing and chemical polishing were physically performed and analyzed. The results are comparatively analyzed on regard to surface quality, processing time and cost. Conformal cooling provides uniform and faster cooling of the product, compared to the conventional cooling. Chemical polishing has shown an improvement in surface roughness of the channels (from Ra = 7,51 µm to Ra = 2,15 µm); moreover, using this technology, the material removal cannot be fully controlled. In addition, using AFM, even better surface roughness can be achieved; however, due to the geometric limitations of the part, the physical application of this technology was not performed.