Wash Out Test Bed

I love to design models with several parts with fit in or swivel parts or hinges, but it comes out to be too large and need sanding, although I have asked from the experts suggesting to reduce 0.2 mm for fit-in and 0.4 mm for moving parts. I don't know the exact terminology for this, I call it "wash-out size" (reduce).

Then it crosses my mind that every printer has different level of precision. So I make this model with FreeCAD -- lines of circles and cubes reducing each step by 0.1 mm -- an