if you are talking about this pattern
You could use that thingy which is used for pasta. And modify it for your needs.
I am not guilty if your wife/girl bust you when she realize you are stealing from her -.-
Moral of the story: When wife is buying stuff for kitchen use, you already think about how you can use those stuff for airbrushing.
edit: I just found old mosquito net for doors which needs to go to garbage. This could also be used as stencil.