If you are asking about making your own, I like to use rebar. If you want them to be poseable I weld a bolt to the shoulder and a nut to the end of the arm. You then thread the nut onto the bolt add another nut and tighten it down when you have it where you want it. I like to use 1/2 x 13 nuts and bolts for this, I put them anywhere that you want a joint. If you soak the nuts and bolts in muratic acid for a couple of minutes it will strip the zinc off of them, and they will be much easier to weld. Use safety goggles, rubber gloves, a respirator, and a pair of pliers to retrieve the parts from the muratic acid. Hope that helps.