Createx water based paints...work great in an airbrush, meant for textiles. They have additives to harden them so they can be used for automotive type painting, but would need to be cleared to be permanent. They are also available under the name Auto Air.
I used to use them on textiles alot, and have used them with the hardener and had it cleared, it works well. I'm not sure how long it will last if left uncleared, but I would think a day or two would be fine.