Multi-scale computer aided design of manufacturing processes of a magnesium bracket for the automotive industry is the main goal of the present paper. Tensile tests at various deformation conditions (temperatures, strain rates etc.) were performed to obtain flow stress data necessary for the macro-scale finite element analysis. The digital material representation concept was used to create a micro-scale model and to evaluate the influence of local microstructural features in the form of twins on material behaviour. An algorithm based on the cellular automata method capable of replicating microstructural morphology with twins was proposed to provide the digital material representation model. The bracket made of AZ31 magnesium alloy was formed at an elevated temperature of 200 degrees C. Description of the study as well as results obtained at two length scales are presented in the paper.