George Pal's stop-motion Puppetoon about a tuba who longs to play a melody of his own.

Public domain (US): Published 1947; copyright not renewed (listed in Wikipedia 'List of animated films in the public domain in the United States', source: Hurst, Film Superlist 1940-1949). Source: Internet Archive (https://archive.org/details/puppe-toon-tubby-the-tuba-1947-1080).