Produced a comparative tensile testing report investigating the mechanical behaviour of metals and polymers. The project involved testing carbon steel, aluminium 2011-T3, nylon 6, and PMMA using Instron universal testing machines. Load–displacement data were converted into stress–strain curves. The report analysed Young’s modulus, yield stress, ultimate tensile strength, elongation at failure, uncertainty, and compared results with literature values. Key findings included steel having the highest stiffness at 215.56 GPa. Aluminium showed the closest agreement with literature at 1.14% deviation. Nylon displayed high ductility at 182.00% elongation, and PMMA showed brittle failure at 1.30% elongation. This strengthened my ability to process experimental data, evaluate uncertainty, and connect material structure to mechanical performance.