The objective of this work was to design a mechanical prosthesis tailored to below-elbow agenesis using a polymer matrix composite material (epoxy resin) reinforced with laminated carbon fiber (prepreg). The design process involved considering the patient's current condition and idealizing the potential tensional stress the component would endure during service conditions. SolidWorks, a computer-aided design software, facilitated the design process, while a customized material library of composite sheet materials, incorporating material parameters and orientations, was established manually. Using the eLamX software, the composite material properties were computed based on the micromechanical model developed by Chamis. Furthermore, to ensure the optimal performance of the prosthesis, a simplified simulation of its mechanical behaviour under service conditions was conducted. This holistic approach, integrating SolidWorks and eLamX, enabled a comprehensive assessment of the prosthesis's functionality and durability in real-world applications, particularly in the context of CrossFit training. Derived from a master's thesis in Materials Engineering (Rivas Hernández, 2023), this work was conducted collaboratively across disciplines, exemplifying a multidisciplinary approach integrating mechanical engineering and materials science, with valuable insights contributed by orthopaedic specialists to prosthesis design and simulation.