Add a few drops of either a store-bought food coloring or a homemade food coloring to the unsweetened coconut flakes and stir them long enough to get an even coloring throughout.
Add more coloring, as needed, until you reach the desired color intensity. (It's a good idea to make the sprinkles slightly darker in color than necessary as they may lighten slightly upon drying.)
Dry the sprinkles
Spread out the tinted coconut in a thin, even layer over a lined baking sheet or a dehydrator tray.
If using a dehydrator, follow the directions for your particular dehydrator to dry out the coconut so that you can safely store it again.
If using an oven, set it to its lowest temperature and turn the fan on, if possible. Bake, checking on it occasionally, to see if the shredded coconut has fully dried. You can speed up the process by stirring it up and spreading it out again, continuing to bake until the coconut has fully dried.
Once fully dried, the sprinkles are ready to be used immediately or stored for later.
Store in well, sealed containers in a cool, dark place.
It is important to fully dry the sprinkles before storing them to prevent microbial growth. (That includes bacterial growth and mold formation.)When stored in a cool, dry place, these should keep for up to around 6 months. Some colors may fade before that, depending on the coloring used. You can make your own shredded coconut or use store-bought. I prefer unsweetened desiccated coconut for a healthier option, but you can use sweetened coconut too if you prefer. (The oils and additives added to some sweetened coconuts may affect the way they absorb the coloring.)You can also choose to use a homemade food coloring made from foods like beetroot powder and turmeric or use a store-bought food coloring.