A few weeks back I was painting up parts for the center foot. I realized pretty quickly that I was missing two pieces though: the ankle sides. For my outer legs, I ordered some of Keith's "beefy" ankles. These don't work on the center leg though, since they are just a little too large.
Just a while ago, I was browsing through the reference images of the ILM Uber droid. They too did not have the ankle sides! Their cylinders are just placed right on the skinny part of the leg. There are no cylinder wedges either. So, maybe I don't need to worry about building the ankle pieces.