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 decided to go with a differential drive layout, which uses two independent rear wheels for power and steering, and a single passive ball caster sphere in the front for balance. I sketched out this layout to make sure it would fit the space perfectly. Finally, I modeled the wheels and the front caster sphere in Inventor. I cut clean semicircular arches along the lower edge of the chassis walls so the wheels can reach the floor. Right now, I have successfully aligned the wheels and the caster on the exact same ground plane, giving the car perfect clearance and leaving the frame ready for the next steps.