M8 INTERNAL thread tap

YOU WILL NEED TO CONVERT THIS STL TO SOLID FIRST,

use this in your CAD modeling as a tool just like an M8 tap,
it has the female M8 thread dimensions and is 50mm long which should be plenty,

DO NOT USE SUPPORT IN THE THREAD,
any printer should print threads without support no problem,
top-tip threads are better and stronger printed at an angle not vertical.

That being said you will never need to print this, just the part it cuts away in your CAD modeling