MIG is really just a glue gun for metal. For things where structural integrity isn’t critical you MIG stuff together by watching a couple YouTube videos and then going at it.

(note that of course mig can be great for structural things, it's just easy to get started)

What I appreciated about metal shop class is the casual (software-like?) attitude towards toolmaking. Would that step go better with a jig? Weld one up on your workbench, and then angle grind everything off when you move to the next phase...

I was using my dad's shop and MIG welder, so he was able to give me an intro. A buddy of mine is a millwright and came over and kindly taught me some tricks which brought me welds up to an acceptable quality.

After learning, I'd have to agree with one of the other responses, learning by Youtube is probably feasible. It's safer than I expected (less concern about touching metal in the ground path) though I'd strongly recommend investing in quality gloves, a quality helmet, and good thick pants, and a long-sleeved shirt / overcoat.

I thought about taking a course but I found this way of learning a lot more fun and engaging (if you're fortunate, as I am, to have experienced people in your life).

Bear in mind that some metals can be toxic when welded.

ie galvanised stuff generates gaseous tin or zinc (~white smoke, i don't remember which). Bad in a confined space like a shed or garage.

So there are some non-obvious considerations that Youtube video's don't seem to mention. :(

you can get cheap welders and use flux core so you don't even need gas shielding.

something like this works well.

https://a.co/d/8XMYx7j

for thin steel or aluminum you really do need shielding gas.

https://youtu.be/X4WkDDnvS7g

Here's that first link but without the tracking linking you to everyone who clicks on it (and vice versa):

https://www.amazon.com/dp/B0B6HL28ZP