Add the shea butter, beeswax, and jojoba oil to the top of the double boiler. Heat, stirring occasionally until completely melted. If you don't have a double boiler, a heat-safe glass bowl on top of a small pot also works well.
While the oils are melting, get the locket ready. If yours doesn't lay open flat then use painter's tape or scotch tape to tape the edges down to the table. Be sure the opening in the middle isn't covered.
Once the oils are melted, turn off the heat and add the essential oils.
Use a small metal teaspoon to carefully pour the lip balm mixture into the inside of the locket. This will harden very quickly! Pour carefully so it doesn't overflow out of the space and onto the rim of the locket.
Allow the lip balm to fully harden on that side, about 10 minutes. Then do the same to the other side of the locket.
Notes
If you have extra left over after making your lip balm lockets, pour the rest into a lip balm tube or jar.