I am a fan of Martin and his Marble Machine(s) and was pleasantly
surprised when, in the latest episode, Martin visits Siegfrieds
Mechanisches Musikkabinett in Rüdesheim am Rhein.  I visited that
museum about 20 years ago, and it has greatly expanded and has many
more machines added since then. Check it out:

https://youtu.be/z8HBiUiYTjo 

Richard Ingram

 [ Also https://www.smmk.de/pages/en/welcome.php 
 [ -- Robbie