The need to create good quality products while implementing design and manufacturing methods that contribute to the reduction of industrial waste has led to the study of lightweighting techniques that allows less use of material for its manufacturing without compromising the mechanical properties of the final product. This paper presents a design methodology that combines two topology optimization methods with the objective of obtaining a lightweight but functional design that adapts to the properties of the material with which the solid product is made and the physical load to which it will be subjected. The proposed design approach relies on finite element analysis whose results are important for the mass distribution of the solid product and the functional gradation of the Voronoi structures that are implemented for weight reduction and effective load management. As a case study, two cubic bodies made of high-strength polylactic acid (PLA) and thermoplastic polyurethane (TPU) were optimized and evaluated through finite element analysis and static compression tests. The results of the evaluations show that the proposed methodology has the potential to create lightweight yet functional designs that can be customized for the specific material and intended use of the final product.