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I was also going to suggest A/C, heating and refrigeration as a side job. This could easily turn into a full time gig and the cool thing is, you're the boss!
After taking a year of basic machining/CNC, I'll be (after taking a couple semesters off for unrelated reasons) switching to CAD and completing a degree in that program. I can "think in metal" just fine, but CAD first will let me "think in CAD". Afterwards I'll do advanced CNC.