Doc Ock was a great addition in ITSV and I'm excited to see how this turns out! I don't know how best to help, but one thing that comes to mind when I see Doc Ocks arms in the movie is the corrugated medical tubing, but I think that if you're trying to make stiffer arms, for looks, I'd take a look at Lowe's or Home Depots piping area, there's probably something there that will looks about right for it.