Aromatherapy essential oils cannot be made simply at home. Essential oils are either extracted using a process called expression, otherwise known as cold pressing, or distilled using steam and/or water, states the National Association for Holistic Aromatherapy. Specialized equipment is needed for both processes.
Expression of essential oils is labor intensive, says the National Association of Holistic Aromatherapy. The oils produced are very volatile as well, which means that they evaporate quickly when exposed to air. Essential oils are highly concentrated, and thousands of plants or flowers may be needed to produce a small amount of oil. For example, 220 pounds of lavender plants are needed to produce just one pound of lavender essential oil, notes the National Cancer Institute.