This research focuses on the development of a working prototype of an alternative aluminum endcap shape to reduce weight and decrease complexity for Portland State Aerospace Society’s Launch Vehicle 4 (PSAS LV4). Low-cost launch vehicles within student teams are often faced with challenges in manufacturing reliable rocketry components that are affordable. Through generous access to a dedicated manufacturing workspace via McCloud Aero Corporation, prototype research for end cap design was able to continue. I conducted analysis on different end cap shapes, different joining and sealing methods through TIG welding, and assessed the structural integrity of the design. These tests were compared against earlier designs with flat end caps, which were heavier and had more complex T-welds. Design processes were documented in the PSAS Isotank Manufacturing and Testing Process Manual, along with spreadsheets tracking welding analysis and manufacturing statistics. During the life cycle of this research, two mini propellant test tanks were investigated and put through hydrostatic test cycles. In conclusion, the results discovered were that aluminum, semi-elliptical end caps with an integral flange were ideal due to student-level manufacturing accessibility, and aluminum is a common aerospace-grade material choice for sophisticated amateur rocketry design. This research project will serve as archival evidence for incoming PSAS and other aerospace students interested in airframe and liquid propulsion subsystems.