I have a more mixed approach.

Decisions or attempts, i try to document them as comments on the ticket. It feels a bit like a conversation with my future self 😄

Things that pop up in my head that I don’t want to forget, but don’t have time to write out, I put in a new tab on nodepad++

Archi things go as markdown in de source code

Investigations and reports in a wiki

All these have all the pros of an engineering handbook out of the box (date, issuer, …)

I only use paper for the stuff I don’t want a trail off and just want to throw away afterwards.

Pure aluminium is only used when you need to have very little reactivity.

General construction steel has >98% weight iron. Around the same as most aluminium alloys.

I start writing the implementation and get the “variable not defined” error and then let the ide add the declaration. It’s less keys to press and misspell.

About D, you could also be programming robots, PLC’s or thermostats 🤷‍♂️