Glitter pens. These are great for eyeshadow, nails, or use to paint small moulds. The pens do not hold a large amount of Glitter, but the applicator is reusable, so add some more Glitter once it's finished and re use the handy applicator to apply in those small spaces!
 Tip the pen upside down when opening as the glitter is held in a compartment inside the pen, so be mindful to carefully open to avoid spillages.
Example photo by Kerry Robertson.