Further, you need to understand fits and tolerances. Maybe even things like thermal expansion properties. I learned this the hardway in my freshman intro-to-eng

Further, you need to understand fits and tolerances. Maybe even things like thermal expansion properties. I learned this the hardway in my freshman intro-to-engineering class when I 3d-milled parts for a basic mechanical clock ... and had the whole system freeze up with friction because I didn't take it into account that you don't have exact fit of parts.