I started by designing a miniature bumper car body with a 2x2x2-inch footprint, including a main chassis and a top cover plate secured by four screws. I set up a two-wheel differential drive system combined with a single internal front ball caster for stability, making sure the wheels and caster aligned perfectly on the floor plane. Then, I selected a 6V, 500 RPM N20 micro gearmotor from Pololu, which has an extended rear shaft. I downloaded the official CAD files and successfully identified the correct part file to bring into my Autodesk Inventor assembly. After analyzing how the motors fit inside the tight chassis space, I realized they are too long to sit end-to-end in a straight line. I drew up a staggered layout concept with spur gears and successfully configured Inventor to generate perfectly sized micro spur gears after adjusting for imperial unit settings. To optimize space even better, I decided to pivot to a vertical motor layout where the motors stand completely upright. I used Inventor’s bevel gear generator to create a pair of tiny 90-degree gears with a perfect 1:1 ratio. Finally, I designed and made this entire internal assembly layout myself by constraining the vertical motors and interlocking the bevel gears directly to the wheel axles. Most recently, I successfully imported the ball caster and modeled a dedicated, custom 3D-printable base mount platform directly on the chassis floor to give it a solid structural home and complete my stable, rolling drivetrain layout.