Ensuring a computer mouse is comfortable, and is gripped easily in either hand is not an easy task. Students need to measure key dimensions on their hands and document the extreme large and extreme small sized hands in a given population (in this case their classroom). Since a computer mouse has to be used by everyone within a given population, it needs to be comfortable, and be gripped easily by the largest and smallest hands - as well as every sized hand in between.
Once the extreme large and small hand sizes are documented, students can calculate the median sized hand (seen in the above sketch). Students design to this median sized hand, but each prototype must be tested by the given population and confirmed. Because the mouse is in essence a compromise in size, it isn't perfect for everyone. But it is nearly perfect for everyone, and that is the target.
After the median hand is traced onto paper, students layout a top view, side view, and end view for the mouse - on top of the sketched hand. The length of mouse is roughly the distance from the tip of the middle finger, to the middle of the hand - as this is the working position. Industrial design students must pay close attention to the grip area on the left and right sides of the mouse (top view), and make the design symmetrical, to accommodate left and right handed users. They must also ramp the mouse from the back to the front, to ensure a natural grip and for the fingers to comfortably reach the front buttons.
Next, the top, side, and end views are traced onto a piece of surfboard foam (11-15 pound density) with dimensions of about 4" long x 3" wide x 2" high. The three views are easily transferred to the foam by poking holes through the layout paper, along the lines of the views, into the foam - then connecting the dots on the foam. Once the three views are transferred to the foam, its time to band saw the mouse form - in two steps.
First the top view is cut out. Care must be taken to not remove the cut out piece from the rectangular block. The rectangular block, with the cutout piece still intact (a bit of tape to keep it in place is ok), is then laid on its side and the side view cut out. The result are cuts that combine the top and side views. What's left is for the student to replicate the end view by hand using a sanding block. And wholla! the mouse form is complete.
Finishing steps involve "skinning" the mouse form (but not the bottom) with joining compound (water based and safer), or with thinned Bondo (styrene based and not safer), sanding the final form, and painting the mouse gloss white. The end result are prototype computer mice, based on solid human factor research, and a classroom full of accomplished future industrial designers.
