I know nothing about making essential oils... BUT... I have done lots of research on extracting oils from plants, which is similar to what you want to do.
There are 2 basic ways to extract "stuff" from plants...
Press it. This is done simply by squeezing the oil or juices out. You can use a garlic press or seed press. Press's can be found in virtually any size.
"Wash" it out. In Absinthe (the drink), it's flavored by soaking assorted botanicals with strong alcohol. Even if you distill the alcohol again, some of the plants oils remain in the drink. That's how they flavor it.<
There are many more than two ways to extract "stuff" from plants.
Pressing extracts some components but is only appropriate for a limited number of plants.
"Washing" is not a method. Here is a brief article on absinthe:
http://www.jeannerose.net/articles/absinthe.html
Plants have constituents that are available by cold pressing, others available from water extractions, others by alcohol extractions, other by distillation and others using solvent extraction. Then there are various chemicals uses as solvents - ranging from simple alcohol extracts to more complex CO2 extracts, and others in between so to speak! Sue