I'm sure this is a super dumb question, but I just don't know the right terminology to google my answer.
So I've made a case for a product with a battery cover that clicks in with some clips.
I want to 3D print both the case and the cover, but some random dude in a Youtube video mentioned that a classic rookie mistake is to make them the exact same dimension, which will produce a really tight fit, or no fit at all.
But I can't find out how to avoid this problem.
So far I've tried to manually make my cover 0.5mm smaller (no idea of this is a reasonable number), but that gets really nasty around all the clips to make their alignment and size correct, because now I have to "spread" this difference along the edges of the cover.
So I gave up on that, as I simply could not get it right, and things kept clipping or have too much space.
I found some videos on tolerances, which is more about variance than the tightness of the fit.
What I want is basically design my cover to the exact dimensions and then apply some "inset" to make it fit smoothly.
This is such a common thing that I'm sure there are smarter ways to do it than manually adjusting all your dimensions by small fractions of a millimeter.