I am at the feeling, if one strand is invisible, a bunch twisted would be as well. I have built a few fluorocarbon leaders but not for the invisibility end, but the sink factor. But, I attach 3' to 14' of fluoro tippet to the leader, now that is where it matters I think. Fluoro is expensive but in all seriousness, fish shouldn't get near the leader, so why waste the money making them? That and it is hard to find large spools of 2lb fluoro which is what I use, but then I generallt fish 6 lb max on tippet (8lb on grass Carp)