In the original predator it appeared that a simple loincloth was used. In AVP, Predators, and the 2018 Predator they appeared to wear a sarong or malong of some sort. The latter appears to have better coverage and held up better to movement.

I am looking at doing a pleather type material from Knoxville foam and fabric. The key to remember with the predator is the species has tribal type structures, but has advanced weaponry. Scuttle was there is some unseen sub species that makes/maintains them. The material needs to look like it is from prey and processed hide of some sort.

https://www.youtube.com/watch?v=c7E6vCYALME

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The impossible takes a while longer and goes over budget too...