This is what I bought on advice from my guru, Gary...
http://www.ebay.com/itm/DC-12V-Push-...item3d32bebbc3
You can just print on a regular piece of printer paper the "EMPTY" and install a flashing LED bulb assembly. It will shine through.
I'm not sure about the metal on the sides. It's just perforated stainless steel. Might even be (probably is) the same stuff used for the flux bands. That said I don't know what the hole size or spacing is supposed to be. I'm sure someone can provide.
Cheers
Steve