I started by designing a miniature bumper car body with a two by two by two 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 six volt five hundred 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 ninety-degree gears with a perfect one to one 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 to complete my custom high efficiency micro drivetrain.