Very cool, thanks for the info.
I'm vegan so I'd be unable to use brain or hide, but yucca plants? Interesting. I think that's a South American thing, but you never know when you'll have one in your back pocket while out in nature, haha.
Ash and cotton, that's pretty simple, and those are easy to find. Ash and fibres is the recipe, I suppose.
How about magnifyers, played around with that? It's pretty easy if you have good sunlight and the right tool, but what about just chunks of broken glass? Could that be done, have you done it?