I have found some very thin cord here in Tokyo (and incidentally some PP webbing sold by the metre).
The sizes and breaking strengths are:
1.5mm (1/16") 148kg (320lbs)
2.5mm (3/32") 263kg (580lbs)
4.0mm (5/32") 627kg (1380lbs)
So, my question is, can I really hang myself (so to speak) with the 1.5mm cord? I weigh 70kg. Even if I can't, surely the 2.5mm stuff would be okay? I have difficulty believing such a thin cord would take the weight, but maybe you all use similar cordage.
The cord is fairly stiff, and has a woven black outer layer, and inside is filled with a bundle of very fine fibres. These fibres do not appear to be grouped into smaller bundles. The exposed end of the cord that I could see looked like a very fine paint brush (or a dandelion head just after it has gone to seed, but before it actually opens).
(I'm still going to try my Claytor Jungle Hammock with the stock-supplied straps and cords, to establish a baseline before I start tweaking it.)