Abstract The submitted monograph is oriented towards application of 3D printing in a structure of a new generation of moulds. As to the content the monograph has been divided into two basic parts, i.e. theoretical and practical. The introductory chapters describe fundamental principles on the basis of which additive manufacturing works, i.e. seven principal types of additive manufacturing. Greater emphasis is laid on the DMLS technology serving as a base for practical part. The second part of theoretical overview deals with inner structure and its optimization. Consequently, the objectives were defined along with theses and methodology of elaboration. The introduction of the practical part offers analysis of the current state of the art as well as of the difficulties emerging in the course of manufacturing of the component parts by means of the DMLS technology. Further on, the monograph shows a case study analysing a shaping intermediate piece designed for plastic injection from the point of view of strength analysis and manufacturing process analysis in case of which the data serve as input information for verification of data after optimization of in-ner typology. The final chapters assess achieved results.