Watching the ferro rod discussion here, I have updated
my necklace with one:
I've made it by cutting a 1 inch piece from my long 5/16" diameter Coghlan's firesteel and joining it by glue and hot shrink tubing with a small glow in the dark stick (green) for the handle. I have decided to use a P38 can opener as a scrapper. It was not very good at the job, so I've made a sharp triangular notch at one end (similar to one on some wire striping tools). Surprisingly it's produced a huge and dense bundle of small sparks without much of an effort (very light pressure required). However I think it might wear off quickly as it's edge dulls. Anyway, here is the notch design:
(click on images to view larger HD sized ones in Picasa).
The working part of the rod is wrapped with another piece of hot shrinking tubing for protection from rust.
The P38 is on the same ring as the flashlight (behind it on the image above), which significantly enhances the grip.
By the way. The black and orange thing visible behind it - is a flat powerful neodymium magnet, which I plan to glue to the back of the flashlight. It can be used for holding the flashlight on metal objects, to pick and recover metal things, and as a string compass - much more versatile thing than a button compass in fact.
Also I've added a quick release clasp for the flash drive, so I can use it without taking off the necklace, or to convert the necklace to a pocket lanyard on a clip.
Still undecided on what to keep as a fire starter device, lighter or rod? The later is noticeably heavier than peanut lighter, but much more versatile on the other hand.