I made mine out of a coathanger, and it has the added bonus of actually securing the airbrush due to the way that the front end is a circle that the nose of the brush inserts into before you cradle the back end. Note that the cup is level, I holster the brush while filling, and the secure hold makes this a one-handed job, which can help when you are holding a part.
I simply started bending the wire coathanger with pliers with the front end, then proceeded into a snug form, testing every bend as I went. I then, as you can see, duct taped it to the stand that holds my respirator. (This stand is actually a Dremel hanging stand that doesn't fit my model, but I got it for a buck.) This holds the brush so well that it withstands getting bumped and backed into.