There are a million variations on making cake sequins, namely from cutting out and painting scraps of fondant or gum paste, or painting commercially made sprinkle sequins. But these all look the same, namely like metallic colored sugar paste circles. I sew, and the last Halloween costume I did for my daughter had me hand sewing about a hundred or so large sequins on her Greek goddess dress. They were thin, metallic, and had a gorgeous luminescence to them. If you are looking to add beautiful gold realistic looking sequins to your cake, you need to actually create them from scratch.
The video from Cakes for Show below shows how to make edible, realistic-looking gold sequins - paper thin, translucent and metallic - from just a little water, gelatin sheets and edible gold luster powder. I love love love this idea and can't wait to create some in my kitchen from the many shades of luster powder just waiting to be played with in my cabinet.
Edible Gold Sequins
3 tablespoons water
1 teaspoon edible gold luster
2 1/2 sheets of gelatin, cut up
In the top of a double boiler, stir the edible gold luster in the water, and then add the gelatin sheets to soften. Place the pan over barely simmering water to melt the gelatin. Carefully mix to avoid adding air bubbles to the gelatin liquid. Pour the metallic looking liquid onto a sheet of acetate (needs to be shiny here so avoid using another medium like parchment paper). Spread thin by holding one side and letting it run. Let the thin gelatin sheets dry overnight. Using a clean and food-safe paper cutter, cut out the sheets into desired sequin shapes and sizes. The scraps can be reheated and reused.