Image courtesy of Adafruit

This robot chassis kit includes everything you need to build a simple roving robot: a chassis, 2 gear-reduced DC motors, 2 rear wheels, 1 front support wheel, and a top plate with mounting hardware. Just add an Arduino with a battery, an H-Bridge, and some sensors, and your robot will be ready to roll!

Buy this roving robot chassis kit from from Amazon or Adafruit.