This study investigates the application of advanced metal additive manufacturing (AM) and topology optimization for the development of a structurally efficient and lightweight 3U nanosatellite frame. Payload weight is a critical factor in space mission costs; therefore, a stock 3U CubeSat design was subjected to structural optimization using specialized Generative Design Software. The optimized model was fabricated using Powder Bed Fusion—Direct Metal Laser Sintering (PBF-DMLS) on an EOS M290 metal printer with AlSi10Mg aluminum alloy. While AlSi10Mg differs in ultimate tensile strength from traditional wrought aerospace alloys, it was selected to evaluate the baseline feasibility of this application. To evaluate manufacturability and preliminary performance, Finite Element Analysis (FEA), including structural and modal response analyses, was conducted. While the optimized design successfully achieved a 53% mass reduction (from 333 g to 155 g) and met the 30 Hz minimum fundamental frequency requirement, static analysis indicated a maximum simulated stress of 287 MPa. Because this exceeds the material’s nominal yield strength of 220 MPa, localized plastic deformation is predicted in the bare-frame configuration under maximum launch loads. This necessitates further design iterations and full-assembly simulations, incorporating the load-sharing effects of integrated panels prior to physical qualification. Post-processing successfully met JAXA dimensional and surface roughness requirements. Ultimately, this study serves as a foundational manufacturability baseline, demonstrating the applicability of PBF-DMLS for nanosatellites.