This is made for ABS and its shrink, so for PLA it may be slightly large print 99% maybe. M4 M5 25mm screws. Fits a X1C Bambu without flow calibration. Needs supports and brim is not bad at the borders of the plate at least for ABS.

Not tested for heat so be sure to check temperatures of the mini before and after mount.

There is no access to the powerbutton as my mini will be allways on so you will need to 

sudo systemsetup -setrestartpowerfailure on

to be able to boot the mac by power cord.

Adding a version with power button access also.

Added the STEP files, as this is the way.