How do you make glitter nail polish?

nail polish is generally an acrylic polymer dissolved in a solvent such as acetone or ethyl acetate along with added pigment to give it color. It's not really something you can whip up in your kitchen using stuff you have lying around, though it wouldn't be a big surprise if there were kits available. If the reason you want to make your own is that you're looking for a very specific shade, buying a white or pearl polish to use as a base and adding your own pigments to make just the color you want seems like it might work.