Oooooo, are you planning a run! I dont have any pics or reference though, I dont think i've seen any out there
... I am interested in obtaining as much information as possible on this classic piece.
You might look at Elso Lopez's blog:
Elso Craft
He usually has a plan link for all the parts he builds but I'm not seeing it with my quick search. If you can't find it, drop him a line. He's a good dude and can probably help you out.
Just to make it more "clear" this isn't the grab arm from the first movie..this is the animatronic arm from the second movie where Arnold removes skin from arm in Dysons home!
I believe you are looking for the reference on the arm in the second movie but that was supposed to be remain of the arm in the first movie?! (they look different, that's why I ask!)
Not working on this exactly, but I am workin on a set of robot arms that would move using probably just about the same methods to get the fingers/wrist to move. Dunno if you're lookin for a fully functioning one or if you know how to make it but after workin on mine and designing it for the last month or so I could get ya well on the way to a fully functioning endo arm. Send me a PM if you're interested (or anyone else, also) and I'll try and get my notes into a coherent form and send them over to ya.