I'm wondering if anyone makes a sapphire case back that'll fit the polerouter. The movement is so pretty and it's a pitty it's not visible

 

might also save the inevitable caseback rubbing from the microrotor

 

I’m not aware of one although it seems feasible.

One of the problems would be that actually there are many different Polerouter case shapes and sizes.

 

There is a German company (the name escapes me) that will make one off display casebooks for you, somewhere around €400 though.
And as above, quite a few casebacks are reference specific, so cannot make a one size fits all unfortunately.

 

Any thoughts about the company name?

 

I assume @CafeRacer thinks of
http://www.customwatchconcepts.com/
Thomas Preik