Here's a new way of doing weathering I've discovered using Bandai marker pens. I've used black, grey and brown. The top one is the blending pen, basically thinner in pen format.



Run the marker pens over all the panel lines and shadow areas. Then use the blending pen to fade and blend everything together. Since it uses thinner (not sure what kind but smells like ipa) it may go through to the base paint so be careful not to use too much.







With a bit of airbrush shading and blending to finish it off.