Good Christmas gifts! These are double cups that screw apart and you use either Modge Podge or spray adhesive to the inside of the *outer* cup where your liquids *don't* go, add glitter (chunkier craft types are best) and shake. So simple!
They call glitter " the herpes of crafting supplies ." It's sticky as hell, yes, but I say: may it never go away. Glitter is forever.