Modeled this after extensively measuring the dimensions of the instruments I have, which are;
Olds Ambassador Cornet,
King Master Cornet,
Holton Collegiate Cornet and
Bach Prelude Pocket Trumpet.
The air path gets wider all the way from the mouthpiece to the bell as it should in a cornet (excluding the valveblock area ).
The mouthpiece is a 5B, as close as possible model of a well known cornet mouthpiece with wonderful sound.
All parts are made or divided into smaller units, enabling this to be printed by using almost any printer, small or large.
As usual I guess it will be a challenge to have the valves operate properly.
Have fun and happy printing.