Here is the image from the stl download from the CMF account on Printables. fwiw, the stock screws are 3mm thread length, and the case screws should be 4.7 thread length, so this should be correct for adding the thickness of the accessory case. I wish they specified the screw thread pitch, as standard pitch I think is .4mm and not .5mm.
The 2.5mm dia. thumb screw on the drawing appears to be the same stock length as the stock drawing, 3.75mm thread length (I measured it - I have my 2pro already). I think it should be at least 1mm longer in thread length due to the thickness of the accessory cover - so beware of reduced thread engagement. Of course I don’t know of a source for this proprietary thumb screw - I imagine you would have to purchase the official CMF cover, which kind of defeats the purpose, doesn’t it? Another option, is to make a custom washer for a longer 2.5mm screw X 5mm length standard screw (and have washers to tune the fit. Also there is no thread lock on the thumb screw, so it relies on the engagement of the face of the 19.3 plastic to stay locked in place.
https://www.printables.com/model/1281036-cmf-phone-2-pro-universal-cover/files
