The general plan is a microsoft mouse clone with 3 physical buttons & a wheel.  The wheel goes above a small button & has no button of its own.  To be sure, this must have been tried 30 years ago.  

Sizing would be done with playdough models.  Prototypes would be 2 part enclosures with no support.  The top would glue on the sides & all the panels would be curved.  A final enclosure would be a single piece with support.  All the electronicals would come from other mice.

TechLead liked the $100 logitech & hence caused it to become the internet's favorite mouse.  It's the same shape as the $9 Logitech M100 from hell.  It has a button below the wheel which can be mapped to the middle button.  The most a lion ever paid for a mouse was $30 for the Logitech M-CQ38.  

Suspect all mice now have the buttons down low & are the same shape because it uses less material.  

Who wants a quiet click if they spend so much on clicky keyboards?

Ferris Bueller frame  #22210 showed a grey eyed Mcrosoft mouse.  Not as boxy as remembered.