I decided to make a mini sumo robot a few weeks ago instead of doing an obstacle avoider. Turns out that once you think about it, mini sumo bots and obstacle avoiders are pretty much the same! The only changes I would need to make would be to the code. Great! Sumos can also double as line followers. So in short, they're pretty versatile. Here is an image of most of the parts that will go into this sucker.