There is a /r/3dprintedinstruments subreddit that if you sort by best of all time has a lot of good stuff.

Fipple flutes like recorders and ocarinas tend to be easy to start with. I also had good luck with the Modular Fiddle [https://openfabpdx.com/download/modular-fiddle-complete-desi... .

HAM radio is whole range of things that were not possible when I was getting into it - first of all it's super cheap to start now, and you can probably bounce RF signals off the moon for less than $100 nowadays. Shortwave radio has always allowed signals to go around the world (by bouncing off the stratosphere). Most likely the new digital + AI capabilities means that a few well positioned relays could make for a very independent, low bandwidth Internet. Solar powered BTS or APs all kinds of experiments are possible...