I started by designing a two-by-two-inch miniature bumper car body with a main chassis and a matching top cover plate. To hold the shell together securely, I added four internal corner pillars and fastened the cover plate down using four metric screws. Next, I figured out the driving mechanism for the car. I chose a differential drive layout with two independent rear wheels and a single passive ball caster sphere tucked inside the front for balance. I modeled the wheels and the front caster sphere in Inventor, cutting clean arches along the lower edge of the chassis walls so the wheels can reach the floor while aligning everything on the exact same ground plane. After evaluating motor options, I selected a high speed six volt five hundred RPM N20 micro gearmotor to give the car great power and agility. Finally, I located the exact engineering model on the Pololu website and figured out how to download the STEP file so I can bring the motor directly into my assembly.