To tell the truth, the gears were built from UnrealEd (just their caps - I added the "depth").

People will think this is "cheating" but hey - isn't it my benefit that I can take advantage of UnrealEd for stranger applications?
I'm going to totally use a way larger palette - you guys would be surprised how bad this baby looks without adjustment layers.
One more thing I noticed - I should have used a very much thinner brush for the front of the vehicle - it doesn't match the details on the side of the tank. In fact, I was surprised that the skirt on the right side almost looked correctly "3D" while the front looked more obviously painted. The lack of depth is my failure to pick out more FACEPUNNNCCHHING colors on my palette.
The turret's cannons also don't cast shadows on the rest of the environment but I liked how round they became. The smudge brush is your friend!

I should have smudged the scratches on the rest of the chassis too maybe...