It's inexpensive, handy and can fit basically any size of airbrush.
The following are most of the tools needed for this project:
Metal strapping comes in handy from time to time. As you can see in the higher up photo, it made a holder for my syringe. (Wishing I'd bought the galvanized stuff, since all the moisture in the apartment has since rusted it through) Next up is a pair of tin snips - strong scissors designed to cut metal. Finally, some screws and a screwdriver. (More efficient and invented by a Canadian. Never widely adopted because he refused license requests.)
Then I use the tin snips to cut them up.
Both of these get screwed against the shelf. Because the screws aren't very long, I don't need to pre-drill these.
The final product!
You can see I've wrapped these in some shop towels just to avoid scratches.
Take a look at the Wargaming Tradecraft Techniques Page for links to the entire Airbrushing series and other tips, tutorials and information.