An essential oil distiller extracts essential oil from plant material. Here's the basic process of steam distillation:
Here's one type of steam distillation setup:
In a commercial essential oil distillery, a large distiller can process
hundreds of pounds of plant material. But if you want to make essential
oils at home, you can buy tabletop versions of distillers.
Here are four essential oil distiller options with at least a 4-star rating on Amazon (as of the time of this writing).
Usually, essential oils are distilled from fresh plant materials, but sometimes the plant is first dried. Dense or thick material, such as roots and seeds, are crushed or chipped before distillation.
If you want to distill an essential oil, you must first know what part of the plant to use. Leaves? Flowers? Roots? Seeds? Twigs or wood chips? Research an essential oil to learn what part of the plant to use.
The amount of essential oil produced during distillation depends on four main factors. The most important is the type and quality of the plant material. The other three are distillation time, temperature in the distiller, and the operating pressure of the distiller.
Other details also affect yield, such as plant harvest time (time of day and year), climate conditions, and the amount of volatile oil each plant contains. The typical yield of essential oil from plants is between 0.005 and 10%. For example, plants that produce a relatively high percentage of oil (such as sage, thyme, and rosemary), require about 500 pounds of plant material to produce 32 ounces of oil.
In other words, if you plan to distill rosemary, expect to use about 15 pounds of rosemary leaves to get one ounce of oil. For a low-yield oil, such as rose, expect to use many more pounds for one ounce of oil.
Source: Aromatherapy: A Complete Guide to the Healing Art
Companies selling specific equipment for distilling essential oils:
Four companies promoting their moonshine stills for essential oil distillation:
Distiller Photo: © Service communication du Conseil général des Alpes de Haute-Provence (Own work) [CC BY-SA 3.0 via Wikimedia Commons and Distillation Diagram Source: Strengthening Post-Harvest Handling Infrastructure to Expand the Export of Herbs, Medicinal and Aromatic Plant Crops, and Essential Oils from Upper Egypt - Scientific Figure on ResearchGate.