In a double boiler, slowly melt your rendered tallow until liquid.
Once melted and slightly cooled (around 120–130°F / 49–54°C), stir in 10–20 drops of essential oil per cup of tallow.
Place the wick in the center of your container. Tape the wick tab or use hot glue to attach it to the bottom of the jar.
Use a popsicle stick to hold the wick in place.
Carefully pour the melted tallow into the container, leaving about ½ inch at the top. Let it cool undisturbed.
Once the candle is fully set (a few hours), trim the wick to about ¼ inch.
Let the candle cure for 24–48 hours for best burn quality.