First, find a uniquely shaped object to dip in diluted bleach. Splatter, rub, and stamp on your T-shirt in different patterns with the bleach.

While it's drying gather up old bracelets, necklaces, and beads.

Once it's dry cut across the top of the shirt, right below the armhole.

Turn the shirt inside out, and use a tape measurer to find the middle and mark it with a pen or fabric chalk. (This is at the top of the shirt on the front)

Sew the elastic on where you made the mark. (Make sure to pull the elastic tight while sewing)
For me, this entire T-shirt was recycled because I cut out elastic from one of my other clothes to use for this. $$$ saver

Take a different material, I just used a different T-shirt, and measure from your neck to your cleavage.
Cut this strip of material thin enough to go through the eye the needle. Cut 2 of these strips.

Sew the 2 strips onto the top of the elastic.

Thread the beads onto the material. Both sides should be in the same bead order for prettiest results :)

Cut another 2 strips of material (thicker) and tie them onto the ends of the beads.

Your done! Adjustments can be made to the back if it is feeling too loose.