First separate your strips of t-shirt into two bundles of six strips each. Then take 1 bundle of six strips and form a loop like shown.
Take your second bundle of strips over and under the first as shown.
Weave the second bundle of strips over and under the first bundle as shown. Repeat one more time. Then pull the knot tightly from both sides, you have now completed the sailor knot.
Once your knot is in good shape, flip to the other side and separate the strands into 4 little bundles of 3 strands on both sides of the knot.
On one side start with the 3 far right strands and cross them over bringing them to the left, then the left over to the right eventually forming a fishtail braid.
Continue to braid until you have reached the end of the strands or your desired length.
Take one of the strands, wrap it around the braid and firmly knot.
Take another strand and slide on a jump ring.
Firmly cross the strand with the jump ring over the braid and tie another knot, so that the jump ring is now on a loop of the strand.
Cut all of the ends off, leaving just one strand.
Wrap the one strand around and around covering up the cut ends and knots from steps 11 and 13. Then tuck the ends if this strand back through the braid.
Repeat steps 4-8 over on the opposite side of the sailor knot .
Add a clasp to one of the jump rings and there you go..
Your old t-shirt is now transformed into a necklace.