Steam Punk Gas Mask Filters

Cool cosplay or costume addition to your standard masks.  Filter slots into the following masks:

shorturl.at/EKWY5

To get the rusted effect I used this paint: shorturl.at/cJWZ2 (Iron).  After painting, lightly paint on a salt and vinegar mix to give it this effect.  Lightly is the key here as it doesn't take much for it to react with the paint.