Cut three length of 5mm nylon cord at least 24 inches long. Hold the cut tips above a lighter to melt the nylon and prevent fraying. Hammer the tip of a framing nail to a post or board and tie the ends of the three cords to the nail.
Hold the center cord and bring the right hand cord up and over both the center and left hand cord. Pick up the middle cord -- what was just the left hand cord -- and pull it over the right hand cord to make it the new right hand end. Continue this braiding process going down the cord lengths.
Slide beads onto the braid as you move down the cords to add custom decoration. Slide the bead through all three cords to ensure the bead stays in place. Slide the metal cord sleeve up onto the braided lanyard when you reach the end. Make a loop out of the braided lanyard and slide it through the metal sleeve so it forms an enclosed loop above the sleeve. Crimp down the sleeve to make the loop secure.
Wrap the open end of the lanyard with at least 12 wraps of the dental floss and slip the metal key clip into the floss so it is threaded through the small loop hole. Cut the floss and tie it off at the lanyard end using a square knot.
Clip the whistle to the key clip on the end of the lanyard and place the enclosed loop around your neck.