Genius reddit user HelpMyInboxIsEmpty made an amazing post on r/3dprinting today: A functional 3D printed trumpet. The only pieces that weren’t 3D printed are the rubber bands and the springs in the valves. He even shared the STL files: Printable_Three_Valve_Trumpet
Thingiverse link: http://www.thingiverse.com/thing:662115/
Link to a mouthpiece below. I’m not sure if it is optimized for this trumpet.
http://www.thingiverse.com/thing:45177
According to the designer, the 3D printed mouthpiece works as well as, if not better than, the metal ones. The trumpet, well, is a work in progress, but impressive none the less.