Indicator Holder (Standard Back Size)

This is a remix of Reese9885's Dial indicator holder:
https://www.thingiverse.com/thing:3259876

I've modified the original to accept standard indicators
(Or at least the ones I've encountered)
I've also added a small spacer bar on the interior of the bracket to allow air to pass into the hotend fan when mounted.

Approximate indicator mount dimensions:

~ 49.3 mm diameter back
~ 31.8 X 31.8 mm center to center hole pattern
~ 2.5 mm through holes with countersink