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.
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.