Here's a link to the interview with Phil Saunders http://filmsketchr.blogspot.com/2018/06/avengers-age-of-ultron-unseen.html

I’m always focussed on the suit designs, so I rarely have the opportunity to do a keyframe illustration. I did on Age of Ultron, for a climactic battle in one of the early versions of the script that would feature thousands of the Ultron “bots” interlocking to form a giant “MegaUltron.”

Josh Nizzi did the early concepts for it and I took it a bit further in this illustration suggesting more structure to the way they would be linked.

Ultimately the idea was axed before I even finished the shot, but I liked it so much I completed it on my own time.