this is just an idea got from a cartoon series in television..here i placed two pictures and and just add gradient to the new layer and blend them linear light and hue..then i erased some of the area to show the skins real

Source links noted. See high resolution. Thanks.

i put these two together because they both have good porn names :D :D

I knew I wanted to rust this car, just couldn't decide what setting to use. I think this one worked out o.k.