The Keaton Music Typewriter
This typewriter is so rare that less than 12 are believed to still exist today.
It was patented in 1936.
Unlike a traditional typewriter with keys for letters, the keys on this typewriter are musical notations.
In the 1950's, it was marketed and sold for about $225 to publishers, educators, and musicians to produce written music without having to handwrite it.
One of the last Keaton typewriters was recently sold for $6000.