Pour a 1/4 cup of liquid castile soap into a 16 oz. or larger bottle.
Add 2 tbsp. of aloe vera gel to the bottle.
Pour 2 tbsp. of oil into the bottle. You can use almond, olive, avocado, vegetable, coconut or emu oil. The type of oil you use will affect the scent and viscosity of your homemade shampoo, so you may want to experiment with different types of oil until you find the one that works best for you.
Add 2 to 3 drops of any essential oil to the bottle to add fragrance. This allows you to customize the scent of your homemade shampoo.
Close the bottle, and shake it vigorously until all the ingredients are blended together.
Add pure vegetable glycerin, 1 tsp. at time, until you are satisfied with the consistency of your shampoo. Shake the bottle well after you add each spoonful to avoid adding too much. The amount of glycerin you need to achieve a standard shampoo texture will vary depending upon what type of oil you used.
Coconut oil is solid at room temperature. This could cause your shampoo to become thick or hard if it is stored in a cool place. Eliminate this problem by running warm water over the outside of the shampoo bottle right before you use it. The water will warm up the coconut oil and return it to a liquid state.