The Mars Sample Return (MSR) mission is a collaboration between NASA and ESA with the aim of retrieving the Martian rock samples gathered by the Perseverance Rover and sending them back to Earth for further study. This report outlines the design of a Mars Ascent Vehicle (MAV) and a Sample Return Lander (SRL) for this mission, with the additional consideration that in-situ resource utilization will be performed. This means that while on Mars, carbon dioxide will be captured, and converted into liquid oxygen and liquid carbon monoxide to be used as propellants. Here one trades off a lower mass of propellant to be brought, with a larger mass of additional systems for propellant generation. This has the potential to bring net mass benefits to the mission, hence justifying a study of its feasibility.