Weigh out the BTMS, cetyl alcohol, cocoa butter, and coconut oil in a double boiler insert or a stainless steel bowl that can be used over a pan of water.
Gently heat (over a double boiler) until all of the ingredients have melted. Stir them well to combine them.
Remove the pan from the heat source.
Weigh out the other ingredients (preservative, essential oils, etc.) and add them to the melted oil-phase ingredients. Mix together all ingredients.
Immediately pour into bar sized mold. (I used a silicone mold meant for soaps or mini loaf-shaped muffins.) You can find something similar here: https://amzn.to/2SAxYMj
Allow the bar(s) to cool completely.
Remove the conditioner bars from the molds.
You can now immediately use your homemade conditioner bar.