While at the auto parts store with my older son today, I noticed that they carry robot fingers. What a coincidence as I've been looking for some. In the past I've used heavy gauage wire but these new fingers looked so much lighter and easier to pose.
I was lucky to purchase their last 2 sets of KwikTwist Giant wire/Foam twist ties. After working awhile with my son on his truck, I returned home and finished a C3PO hand using a glove and the Tk409 hand parts as well as a small piece of foam for the palm. The preliminary test looks pretty good. I'll dye the gloves charcoal grey (with my all purpose aerosol dye) and then position the foam a little better than this initial test. Adding a piece of pvc pipe at the end gives you something to mount them to in the forearm.