Just one thing that ought to be reiterated in the posts on this topic:
there is one utterly superb mechanical musical instrument that can be
pretty well had for free.  It has a vast repertoire of material, from
the very oldest to fairly up-to-date music, in plentiful supply. Many
are simple enough that a smart teenager can restore them, and they will
give a lifetime's pleasure.  It hits all the modern "interactive"
buttons as well.

It is, of course, the player piano!

It's extraordinary how the finest instrument available in the hobby is
the cheapest and by many the least well-regarded. Is it in low regard
because it is too cheap?  Big mistake.  Get a sort-of-working player
into a house and the kids will most likely use it, and some will get
more interested.  That is how I started, retubing our nearly-dead
instrument when I was fourteen.

There are quite a few players now appearing on YouTube, some good and
some rotten, but at least they're there.  What somebody needs to do is
create a five-minute YouTube video giving practical regulation, repair,
rebuilding tips, simple and to-the-point, to keep the viewer's atten-
tion.  Get the information out there to a new generation, so that not
only do they see the instruments working but they can also learn how to
make theirs work. A good idea?  Maybe, maybe not; but you have to try
new means to reach new people, and talk to them in a way they'll listen
to.

Julian Dyer