This has been a question I have had since I started learning CAD.  If I have a part with a tolerance, something like maybe a bar whose length is 4.00 - 3.95, should I model it using the min, the max, or something in the middle?  I can put tolerances on the drawing, but i'm really wondering what to do about the part itself.  Ive asked a few people but even my teachers seem to disagree on what preferred practice is.