in the past I have used the mesh that is used to line bottom of cabinets and drawers... stole some from the wifes supplies...hehe. worked pretty good but you have to make sure it does not strech or move. painted black over it and then took it off and painted gray.

I got it from here:
[link=http://www.rctech.net/articles/painting_hauntedmyst3.shtml]http://www.rctech.net/articles/painting_hauntedmyst3.shtml[/link]

it is about 3/4ths of the way down the page...