Abstract: A computer mouse includes a mouse housing for supporting a ball therein. The housing includes a top coupled with a bottom. The bottom includes a single-piece body without a belly door, and the top includes a single-piece body having at least one button formed integrally with the single-piece body. The bottom includes an opening having a size smaller than the diameter of the ball. The opening is sized to expose a portion of the ball to roll on a working surface. Rotational members such as encoding wheel shafts are disposed near the opening to contact the ball and rotate synchronously with the ball. A ball support is disposed between the top and the bottom for receiving the ball upon turning of the mouse housing upside down. The ball support has a sufficient depth to allow the ball to drop away from the opening in the bottom and to expose and render the at least one rotational member accessible from outside the housing through the opening.