Just wondering if anyone out the has made one of these tinder cords to be used with the flint and steel? Just have a few questions... 1. What size of cotton rope to you use? Which size is ideal? 2. How do you keep from knocking all of the charred stuff of the end of the rope, while trying to light the fire? 3. How long is the metal tube supposed to be? 4. What is the purpose of the metal tube exactly? Haven't really found a comprehensive write up on tinder cords. If there is one on the site, I'd appreciate be redirected to the info. Been picking bits and pieces... Thanks in advance!