These are pictures of a finished mouse. Yours will probably be much better!

You should note the funny shapes of the microswitch actuators. These need quite a lot of fiddling with to stop the mouse from getting hung up in corners. It would be better to mount the microswitches vertically and fit balsa actuators on them. The wood can be easily sanded to change the shape to the best one. As the actuators then move without rotation the shape is less tricky to arrive at.

You should also note that the battery position is also critical. Moving it around will affect the traction available on each tyre.