MIDI commands are transmitted over USB serial because it is based only on Arduino Nano, but it is possible to add a real MIDI output too with one IO pin. I might do some minor tweaking on it but the project is complete and working accurately with good stable response. The case was designed for 3D printing and to be as small as possible, with replaceable mouth pieces. Supprisingly largest part was the air flow sensor and not the Arduino.
MPXV7002DP air flow sensor
3D printed case (colorless PLA for mouth piece)
Rivets attached to wire to act as capacitive finger sensors
Resistors to make the capacitive sensing circuit work