This study presents the design, modeling, analysis, and structural optimization of a 1 U CubeSat frame fabricated from Polyether Ether Ketone (PEEK) using additive manufacturing techniques. The primary objective is to minimize the total mass of the CubeSat while ensuring sufficient structural integrity to withstand the mechanical loads encountered during critical phases of launch, including liftoff and stage separations. Finite Element Method (FEM) simulations were conducted in accordance with the design specifications for 1 U CubeSats established by Cal Poly (San Luis Obispo, California) and the specified launch load requirements. Various geometric configurations of the CubeSat’s faces were tested to explore structural optimization potentials. The results of these simulations were analyzed to refine the CubeSat’s geometry, achieving significant mass reduction without compromising structural strength. The application of advanced additive manufacturing techniques enabled the production of these optimized structures, regardless of geometric complexity. This study demonstrates that the integration of FEM processes with cutting-edge 3D printing technologies can yield high-strength, lightweight structures. This approach proves particularly advantageous for 1 U CubeSats, where the reduction in structural mass allows for the allocation of additional weight capacity to other systems or subsystems.