I did not have a mini mouse but instead wanted to use a leftover mouse (from a dead computer) I had lying around, a classic PS/2 type Microsoft Intellimouse and convert that into a bus of some kind. I was thinking what kind of material I could use to make a bus out of this mouse, and finally came up with the idea of using modeling paste, which is fun to use for children as well. Here is how it goes.
Step 1: Preparing the Mouse
Step 2: Modeling the Bus
Note: it is important that the lower side of the bus will stay as flat as possible, otherwise the mouse (in this case the classic ball type) will not function properly any longer. You can roll the roof of the bus to get a nice round top.
Step 3: Finishing the Model
(and yes, this mouse has the disadvantage of having a 'tail' - and so does the bus. Just fantasize it is being towed or something...)
Tip: to drive the bus more smoothly, you may need to put some soft tape underneath, like the soft side of velcro. The tape should not be thicker than the sliders of the mouse.