I make this instructable because I have searched and searched for how to weather cardboard, but had to figure out my own techniques. These are techniques I have developed ove a while and use regularly for my armor.

Supplies

-something to be weathered(I used mando armor)
-brown acrylic paint
-black acrylic paint
-silver acrylic paint
-black spray paint or an airbrush with black paint
-water
-a medium paintbrush
-a craft knife
-a whole bunch of paper towels, or a rag you don't mind throwing out

Step 1: Gashes and Scratches

This step may seem usless but really pays of when you do a brown/black wash. For deep gashes, draw a line where you want your gash to go, then use a craft knife and cut into the cardboard at angle on both sides of the line, after that is done paint over the gash is silver. For scratches use an craft knife and lightly, but not too lightly, run the tip of the blade at random over the surface you want scrached.

Step 2: Blaster/Scorch Marks

Start with using black spray paint, or an airbrush with black paint and spray the shape of your scorch mark onto your thing. After that has dried, dent the middle of the scorch mark with something such as the back end of a paintbrush. Once it is dented go over the center area with black acrylic paint to touch it up.

Step 3: Black/Brown Wash

For the black/brown wash take 2 parts water and 1 part black or brown paint and mix them together. Brush a thick layer of the paint mixture of your piece and wait about 15 seconds, this wait allows the paint to soak into to the gashes and really make them pop. After the fifteen seconds are up dab of most of the paint with your paper towel or rag.