Needing an extra-wide strap tutorial, please.

I would like to make a guitar strap for my niece but I'm having difficulties in finding a flat, extra-wide weave/knot tutorial. I'm drawn to the herringbone, trilobyte and conquistdor weaves, yet the pages I'm finding either aren't wide enough(approximately 3 1/2") or are items for sale. Is anyone able/willing to direct me to a comprehensive tutorial? I'm quite new to knotting and the patterns are no good for me, yet - I need an actual how-to type set up. I would greatly appreciate any help. I've included a pic of the general look I'm after, though it's a bracelet rather than a strap.
Also, I'm going to attach - probably by sewing - this strap to scrapped strap ends.