Okay then, here (bottom one) is what I made tonight:
Partial gutted (yeah, you can do that) to get it running tighter, and now all knots instead of cores or crimps. My knots suck so it it a bit twisted but that shouldn't impact anything and I'll get better. Will probably stop shrink tubing the mid knots, but will continue covering the bottom, as it's sealed off with melting the cord ends together so could be abrasive or very slightly loud in the wrong circumstances, so it's covered.
And... out of beads! So will mail this to someone, all other orders need to wait a few days.
Also looked up bead material. Neoprene so appears that it doesn't really sustain fire, etc very well either. Tried lighting a spare on fire and it got an orange flame, smoked a bit, but didn't sustain once the ignition was removed, got soft but didn't drip liquid rubber, etc. So while I am not going to FR certification, the kevlar one seems pretty damned safe if that's a concern.