There was indeed an aluminum piano on board the Hindenburg.  It was
custom built, of course, and was apparently somewhat of a marvel.

I used to know who built it, but memory fails. In the movie, the
character Joseph Spah (an actual Hindenburg passenger portrayed by
an actor who looked just like him) plays a humorous song on it, much
to the embarrassment of captains Pruss and Lehman, not to mention the
Luftwaffe captain, as the song is mocking the Nazis.  Of course, the
piano was not recreated for the movie, so it didn't sound like an
aluminum piano

However, in piano tuning school, we had a spinet piano with an
aluminum plate.  It was very lightweight (two people could easily
lift it), and sounded hideous.  I don't recall the manufacturer...

We had a number of odd pianos there.  We had a fully restored Mason &
Hamlin screw-stringer, a Chickering with a pot metal action (unplayable
and impossible to work on), a Steinway upright with a burled walnut
interior, a piano with no pinblock ( special pins were driven into the
plate itself), and an 1875 Broadwood grand.

The school shut down shortly after I left, and everything was sold.
I wonder what became of all the oddities...?

Bryan Cather  -  Arlington Texas
(For all you coaster freaks, I'm right across the street
from Six Flags!)