Place the lip balm tubes in the filling tray, and gently pour the mixture into them. Then scrape away the excess using the spatula.
Using the low heat setting on your heat gun, smooth out the tops and release any air bubbles that have become trapped in the lip balm.
Let the lip balm set for at least half an hour before removing the tubes from the tray and putting on the lids.
Notes
You can render tallow yourself or purchase tallow. I try to use tallow from organic, grass-fed cows or at least cows that I know were raised in a healthy environment.
Homemade lip balm is shelf-stable and can be stored in a cool, dark location for up to a year.