In this paper, we discuss the design and engineering of the PolyBot board, a custom robot controller board. This board has many features which make it suitable for use in the design and construction of a simple mobile robot. We outline the design decisions made such as: microcontroller selection, input and output features, board layout, connector selection, and software. We discuss our experiences in using the board in an undergraduate robotics class at Cal Poly State University, San Luis Obispo.