If you’re looking for a handsome chassis for your robot that’s small, but has a little extra space up top, consider Adafruit’s Mini Robot Rover Chassis with a top metal plate. The plate adds a bit more storage that could be used in a myriad of ways.
The parts are made of aluminum and anodized red, for a crisp look. They can be used to build a small two- or four-wheeled robot. While it comes with lots of mounting holes, additional holes can be easily drilled to customize your bot exactly the way you want it. The plates can also be cut, if necessary.
Both the top plate and chassis can be purchased from Adafruit for less than $15 combined.