I must say, I'm a little chuffed about this project.
I kinda love it.
You will need:
an old watch (or watch case, if you're making a necklace)
I used my vintage watches as bracelets and
made a necklace from a case that was missing it's wristband.
Use small pliers to remove the pin, to pull apart the front and back of case,
then remove inner workings. Fill one side of case with a mound of fine glitter.
Put front and back together, snap shut.
Either glue the watch pin back in the hole or fill the hole with strong glue.
TIPS: a)The more glitter you put in, the less movement you will have. And vice versa.
I did the large bracelet about 75% full and the small one about 90% full. I like both results but I'm really into a lot of movement - it entertains me to shake the bracelet around like a snow globe.
b)If you applied a layer of mod podge or glue on the bottom base, some glitter would stick and give a more uniform look and less movement, if that's what you're after.
Disclaimer: I can't guarantee you won't get glitter all over you in this process. ;)