Just a test of a super simple mini sumo robot that uses cheap (yellow) gearmotors. Board mounting is for arduino with a motor shield or no board mount and a breadboard up top. There is space below the motors for a 4AA switched enclosure, but i haven't worked on a mount for it other than hot melt or double sided tape. This keeps the center of gravity low.
Great start for a really cheap mini sumo bot, more to follow. Let me know if you have any ideas - I am trying to start a local mini sumo competition (Long Island to Manhattan) where the price constraint is under $100 per bot for ages 18 and under.