To build a successful mouse trap racer in physics class, start with a sturdy base that can support the mouse trap and wheels, using materials like wood or cardboard. Opt for large, lightweight wheels that roll smoothly to enhance performance. The strength of the mouse trap is crucial, so select a powerful one to maximize distance. Experimenting with various designs can lead to better results, and lightweight materials like balsa wood or plastic will help increase speed. Testing and making adjustments before the final race is essential for achieving the best performance.