The Keaton Music Typewriter is an extremely rare typewriter that prints musical notation on to sheet music paper. The typewriter was invented in 1933 by Robert H. Keaton and was originally available with 14 keys. A 33 key version (pictured) was released in 1953. Exact production numbers are unknown, but estimates for the number of machines still in existence range from 6 to two dozen.
For more info, check out the 1993 Issue of ETCetera by the Early Typewriter Collectors’ Association.