The Toaster Project is a good example of this:

https://www.youtube.com/watch?v=5ODzO7Lz_pw

https://www.amazon.com/Toaster-Project-Attempt-Electric-Appl...

He attempted to build the basic components of a toaster from scratch. Smelting metal, molding plastic, etc. The book is a tough recommendation because he sortof gives up on the later parts and limps to a finish, but overall its a fascinating look at how difficult these processes are if you build them up from scratch.

HTME on Youtube also goes into the process of making seemingly simple things and the time and effort it takes: https://www.youtube.com/channel/UCfIqCzQJXvYj9ssCoHq327g

One of the more famous videos is where it takes them ~$1500 and 6 months to make a chicken sandwich and they still used a lot of equipment that they didn't make themselves.

https://www.youtube.com/watch?v=URvWSsAgtJE

  it takes them ~$1500 and 6 months
  to make a chicken sandwich

I watched that video and there's nothing really explaining what went into that price. Did they include the flights to the coast to gather salt? Hiring the boat? Renting an apartment to boil the sea water down?

It does seem to be a rather meaningless exercise and depends on what you start with. If you have a back garden or a tiny plot of land, you can easily grow the required ingredients and raise the chicken for far less than $1500, although the wheat will take that amount of time to grow. If you start with absolutely nothing and insist on farming wheat in the middle of San Francisco, it can certainly cost far more than $1500 to get your chicken sandwich.

I dabbled in electronics, then electromechanics then mechanics.

I'm now convinced that almost no software engineer is worth its title unless he made some physical apparatus on any complexity. Even a pair of scissors.

I think you also have to argue for why, for your comment to be meaningful. Otherwise, I could just as well state that "no software engineer is worth their title unless they've competed in horseback riding, specifically dressage."

Why? That's akin to saying a mechanical engineer isn't worth their salt unless they know how to design and implement software. They're two different specialties that do different things. To be a good mechanical engineer you absolutely don't need to be good at making or even have tried to have make software.

Cross-discipline experience is invaluable, especially across several domains. One begins to appreciate commonalities, uniquenesses, and the infuriating significance of details only apparent on in-depth experimentation and iteration.

As with usability testing, small-n samples, say three to five, go a long way.

Do you have cross-domain expertise yourself?

That's all true, and almost entirely irrelevant to the (very strong!) claim "a software engineer who hasn't built some mechanism is not worthy of the title".

But why specifically manufacture of consumer goods, when there are so many other disciplines, like horseback riding, nursing, human resources, and so on.