Below is a close up of the pressure gauge which resides on the end of the hose on Packrat's mask, from the upcoming movie After The Fall. Below I have listed the three steps I used to transform a brand new shiny gauge to the grungy one shown.
1. Sand the nickel coating off of the edges of the copper ring that surrounds the glass.
2. Cover the entire gauge liberally with a brown wood stain, wiping off most of it.
3. Spritz a little yellow brown aniline dye onto the glass cover.