I use stainless steel tubing, 1/8" OD.
Thought about other materials, but I had some old stainless steel brake line tubing lying around (have no idea when or where acquired). So I just used that.
My hammock is hung from the s.s. toggles so I wanted something I could really trust without any doubts. I would hate waking up in the middle of the night for the usual trip and then wondering how much longer those toggles I'm hanging from are going to last. And yes I would do that.
The s.s. brake line tubing worked very well and so when I needed more toggles I just purchased 3' of s.s. tubing and cut what I needed.
At 0.20 oz/toggle, I can live with the weight and not have to be concerned about the capability of the toggle.