Welder? not sure I know a live 70 year old that did it for 40.
Machinist? Getting replaced with a robot every damn day, a big goal of industry. Be a robot mechanic or programmer...the future in manufacturing that's already here.
HVAC? Yeah!
Electrician ? yeah!
Plumer? yeah!
Replace the top 3 with trained mechanical contractor & never be without work.
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A top welder is never out of work and I welder just shy of 50 years and I'm 71 and still going strong. I'd wager that I made more money than any of the other trades listed