I printed the parts once and measured how far off the critical dimensions were from the actual model (it was consistently oversized by about 0.1 - 0.3 mm). I altered the CAD model by that value and got it (as far as I can measure) spot on for the second try. When designing these things, properly constrained models is an absolute must! Being able to change one single dimension without the rest of the model breaking/needing tweaking makes the whole process much easier.
Spoiler: