Dry sponges cut into 1/2" squares (any small shape will do)
25" of .5mm Stretch Magic cord
Cut and thread a needle onto a 25" length of the Stretch Magic cord.
Thread 1/2" pieces of sponge onto the thread and tie the ends into a knot when it’s full.
Wet and ring the water out of the sponges then put the necklace in the freezer. Wait a little while (30 minutes or so).
Take the necklace from the freezer and put it on-cool off!