Add coconut oil, shea butter, and sweet almond or olive oil to a double boiler with 1-2 inches of water in the bottom. If you don't have a double boiler you can put the ingredients in a metal or glass measuring cup, or a small mixing bowl that you can place over a saucepan. Then place your cup or bowl in or over the saucepan which is filled with a couple inches of water.
Heat mixture over low heat until the shea butter is melted.
Remove the top of the double boiler (or take out the measuring cup or bowl, using hot mitts) and allow to cool a little.
Carefully, being sure not to inhale any of the powder, measure out and stir in the zinc oxide powder. It's recommended that you use a mask to cover your nose and mouth during this step.
Add the optional essential oils, and optional cocoa powder. Stir well to combine.
Store sunscreen in a small airtight jar.