This is 'great' Ultron from the Annihilation: Conquest series. He differs from the usual versions in that he wears a cape and has 6 eyes.
Ultron was fairly intricate but the base choice of a quite robotic Movie Realisation figure made it a little easier. I have always felt the most important part of Ultron (let's face it, he has a pretty generic metal villain body) is his head. I spent a long time tinkering with him to get the Jack O'Lantern face to a point I was happy with.
His cape was made with papier mache covered in latex. He is painted with several different silver shades.
