2 major mods on this custom.
Megatron's left arm was a little...small. It was replaced with a ratcheting arm with more bulk, and ROTF hand then attached to it's end. This arm stores up top, under the tank canon turret.
His larger arm, a tightly fit and snug ball joint was added at the elbow, allowing free range and articulation in that arm.
He was primed with black fusion, then coated with house of kolorz gloss black, followed by a layer of alclad. Next came some washed and dry brushing, about 14 different shades of silver and rust. Detailed with copper, gold and brass. Finally, washed with Tamiya clear "smoke"
I wanted to give the metal a tarnished and worn look. The "cracked" metal look was achieved by air brushing clear coats over wet paint, then flattened down with a stiff brush.
Also, etched in Cybertronian symbols in random spots with a dremel "engraving" attachment.