Once upon a time, I considered hacking apart an old Microsoft mouse and using its guts as the basis of a MAME Tempest spinner...

On the bright side, I've heard you can get actual Tempest games pretty cheap. Their vector monitors were one of the earliest color vector displays made, and they tended to blow a certain component with regularity. So as long as you know how to fix that problem component, you can pick up old blown Tempest units pretty cheap from people who don't know how to fix them.

At least that was their status several years ago when I considered getting one, but haven't looked into it recently...