I don’t have much (or more exactly any) experience with Airbrushing, but the first thing i noticed with my new tool was the bad fit for my rather large hands.
A bit of modelling in Cinema 4D and a couple of prototypes remedied the problem quite nicely.
The handle is easy to remove for cleaning.

On Thingiverse

AirBrush Handle STL and C4D

Airbrushgun02 Airbrushgun01 Airbrushgun06

Airbrushgun05 Airbrushgun04 Airbrushgun03