Manual skills that pay well and can be self taught?

Plumbers that work with the brown stuff. Had a drain backup and the guy that showed up said it was $150 an hour. minimum 1 hour. As he was working he kept getting calls. He said he had 6 more calls that day for drain issues. The he was getting he had to schedule for the following day. Sometimes when im neck deep in tech crud for hours tracking down a problem or trying to cram in yet more "needed" features I sometimes wonder if ditch digging or working in the brown stuff would be much more rewarding. After all you can see the problem is resolved when your done with a plumbing or ditch issue. With IT you never really know if it will crop up again or not.

This isn't manual work, but high paying jobs often require certifications. The burden of acquiring the certification reduces the available labor pool.

My suggestion is to figure out which professions your state regulates, see which of those is best to become certified in, and get that certification. It depends on the state, but some professions have a very favorable time/pay payoff and others have a horrible payoff. In my state, it's easier to become a real estate agent (~250 hours) than it is to become a certified barber/hairdresser (1000+ mandatory training hours!!)

Assuming you pick something good, if you're smart and can pass an exam, it should be no problem. The best candidates where I live are starting your own car dealership, insurance sales, or maybe real estate, although those aren't manual work.

If you want something easier that's hands-on, where I live it's bartending, which requires a license here. My state pays the full minimum wage for tipped employees, so bartending ends up being roughly a ~$20/hour at worst ($15/hour minimum wage + ~$5 in tips per hour as a low estimate). If you bartend at a better place, you can easily make a lot more, although maybe this is not the best career choice during the pandemic.

Many of the trades still pay over the average mid-level Software Engineer here in the Midwestern US. Of course who your employer is in either field is going to make a difference.

If this is the direction you're trying to go: I grew up in the trades and keep trying to bounce back into that direction, but always get pulled back towards the technical aspect and/or implementing tech into the business side once anyone in management figures out you can as much as use the Office Suite. I eventually got backed into a spot of not enough "professional" dev experience to leave, and old enough to not be desired to start over as a junior.

If you're dead set, though, I'd start with HVAC - I think it's the best balance of interesting with a little manual effort to it. Includes a bit of many trades (plumbing, electrical, steam depending on the area). The main walled garden is the EPA-608 cert and it can be obtained fairly easily with little study.

A childhood friend, now a plumber doing work for high-security installations was making more than me. He is not the smartest. His dad is a lifer from the system and his mom is on the zoning comish.

Trades that are easy to learn build a fence around themselves, just like everyone else. Certifications, permits, mandatory insurance and lack of documentation. You are expected to earn less as an apprentice to "pay off your dues". A different trade with "make your bones" comes to mind.

So to learn yourself, you also have to learn to identify niches that would be easy for you to enter, but not for the competition. That is hard.

working for someone else, probably not many. However if you "start a business" in just about anything you can do it.

for example basic mowing can be 50/hour now that neighborhood kids are no longer cutting lawns. The hard part is the utilization is low due to travel time.

pool maintenance

trades such as laying tile, installing drywall, painting, cabinetry all can pay well if you are working directly for clients.

I have a mate who works a contract welder and seems to make pretty decent money and have a lot of flexibility.

Trash men and construction come to mind first.

Most blue collar jobs can be self studied, but usually require some sort of certification or license. Mechanics, welders, plumbers, electricians, etc can make good money but require some training/licensing.

Tattooing - the good ones do more than the average software engineer in my country

Car mechanic. If you specialize in certain niches, it pays quite well.

You could consider painting or landscaping residential or commercial properties.

You learn by upgrading the residences of family and friends well enough to show off your efforts, gain recommendations and launch free-lance work.

At some point you may need a license or registration and you should be prepared to be bonded, insured, and proficiency tested, or you may need to work for another licensed contractor before you can _graduate_ to going commercial on your own.

Electrician. You gotta know your circuitry, how to drill and cover the wall work, how to spot shoddy wiring. How to make sure the power is off in the house before you start working (otherwise you will die). How to build self hosted security camera systems (a real good money maker).

You have to be punctual, reliable and have good estimates (always over estimate then bill lower by a small amount, like Scotty in Star Trek did).

They command as high an hourly price as they want without all the wet work HVAC has to do, and no work with gas pipes so you don't accidentally blow up someone's kitchen.

Floor tiling

Did it in during the lockdown. Self-thought, tutorials on the web and some tips from people. Got stressed for a moment, but then it gets quite easy. Would not do it myself if it wasn't for the lockdown.