Several years ago I was CO of a Young Marines youth unit and we made these belts. Once you get the hang of it, it goes pretty fast. The belt is made of paracord or other strong cordage and in a pinch you can easily unravel it to use the cord. Here is a link for the site that tells you how to make it.
http://www.slatts.ukfsn.org/slatts-knot.htm
http://www.slatts.ukfsn.org/slatts-knot.htm