The additive manufacturing technology provide new possibilities to design products with increased stiffness under consideration of material saving. The optimisation methods establish a technical framework to develop products with a very high complexity. Finally, it is possible to produce any shape and geometry by combination of the additive manufacturing technology and the optimisation methods. One topic of the present work is the investigation of the potentials and restrictions of lattice structures used for optimisation under consideration of the additive manufacturing technology. Furthermore, the influence of different heat treatment cycles on the microstructure and the mechanical properties of additively manufactured parts is investigated. After the general development and investigation of the relationship between these topics, several applications are designed and analysed to evaluate the theoretical statements. The first case study is a patented multimaterial hybrid joint manufactured by the help of additive manufacturing and injection moulding. The second application is the applicability of lattice structures for high performance and conformal cooling systems for tools. Based on this approach, the manufacturability and applicability of lattice structures within heat pipes or thermo syphons is discussed. Finally, extended design rules are defined for the use of lattice structures in new developed parts. For the automated calculation of the mechanical properties of lattice structures and under consideration of the analytic and practical investigation results, a MatLab code is presented.