As far as I know it's the same kinda screen/mesh that's used in screen-doors. You can find it at any hardware store I'm sure. I was kinda curious if it came in different grades or thicknesses, because the kind I found in my basement is really, really "soft." Almost brittle. Field trip to Home Dee-pot!!
If you go to any kind of Michaels or Hobby Lobby, they have model metal mesh, i got some, its one huge sheet of it that you can cut. Its real good cause its cheap and you can overlap it to give it a real cool look. Good luck on this mate.