In our RPG campaign, Norman's character is piloting a Longbow Mech. Norman asked me to paint his model in the same style as the rest of the Mechs of our Mercenary Unit (which were all painted by me).
I got the model primed in grey, with… some… mold lines removed.
First step was to give it a zenithal airbrushed coat of white.
Then followed a wash of 1 part yellow ink, 1 part brown ink and 2 parts water.

