The paper deals with the objectification of the methodology of design of large-scale modules of mobile working machines (MWG) using the principles of topological optimization (TO) and its application through additive manufacturing, namely the WAAM (Wire Arc Additive Manufacturing) technology, and the verification of this methodology. The methodology involves a sequence of steps from the selection of a suitable module, its comparative subjecting to TO using available software tools, to the subsequent implementation of the available module through the dynamically developing additive manufacturing technology from affordable materials. Safety requirements in terms of EN ISO 3471 were chosen as a benchmark. It can be concluded that the above methodology represents an efficient design for the development of the MPS module with regard to its safety, functional and manufacturing parameters. The comparison of G3Si1 and ER 5356 materials focused on strength characteristics and weight. The results show that the ER 5356 material performs better in terms of overall cabin weight, achieving a weight of 422 kg, a reduction of 28% compared to the original solution.