You should check out this thread for a general discussion about tolerances. Even using a mill/lathe, you’ll probably be hand filing to get the best fits possible. Which could marginally change the length and angle of the next miter……which could change the length and angle of the next miter…….
Don’t stress about hitting the CAD dimensions perfect, leave yourself wiggle room with your hole saw and walk the miter in with a file until it fits tight.