Hi, see my follow up on distilling medicinal herbs.

Many people confuse essential oils-- pure plant oils extracted by steam distillation, chemical extraction of heavy pressing-- with mascerated or infused oils.

The first (essential oils or EOs) are the true plant oils-- all plants have some oil in small quantities. They are the type you buy in 1/2 oz quantities in the health food store and are highly concentrated, thus used drop by drop-- they can be skin irritants if not diluted in a carrier or base oil and are ALWAYS toxic in high doses. Most aromatherapists/herbalists caution about using them internally. Most essential oils are extracted via steam distillation, a few by chemical extraction or physical extraction (heavy pressing, as in citrus oils). Home distillation-- usually steam-- is possible but not usually commercially economical unless you also own the farm or have access to lots and lots of plant material. While you can build a still at home, it's probably easier to purchase one that you know will work. Again, it takes a lot of plant material to make essential oils, less to make simple hydrosols, which contain the water-loving properties of the plant.

Infused/mascerated oils, on the other hand, can be produced in large batches at home with no more equipment than clean jar and a sunny windowsill. Infused oils will carry all the oil-loving herb properties of the plants but will not be as strong as essential oils. Their value is underestimated by a lot of people because they are so easy to make.

If you simply want a mint oil that you can use for flavoring or massage, macerate the herb in the vegetable oil of your choice, approximately 1/3 volume herb to 2/3 volume oil. Set in a warm, sunny location & shake daily for 2 weeks, then strain the oil. Add more plant material if the oil is not strong enough for your liking (be careful with mints, they can get too "green" & may sting if they sit in the oil too long). This type of oil will last 6 mos to a year depending on what your base oil is-- almond & nut oils will have shorter shelf lives than olive. Oils can be refrigerated to extend shelf life or a little rosemary EXTRACT can be added to prevent spoilage. You can then add the oils to your balms, salad dressings, massage oils and bath & beauty products and know you're getting the herbal benefit of the plant.

Right now on my windowsill (it's only mid-40s here at the height of the day but the jars still warm up), I have quart mason jars of: calendula, chamomile, patchouli, jewelweed, myrhh, dragonsblood, ginger and sandalwood mascerating. I will put these oils into bath & body products I make. This will change as the year progresses and I need different oils. I regularly mascerate garlic, mushrooms, and garden herbs for dressings & cooking. When the St. Johnswort blooms, I head out every morning & pop the flowers into olive oils for a gorgeous red oil that zaps nerve pain & heals small wounds, as well as helps stave off SAD-- so you can use fresh herbs as well as dried, with the warning to harvest them when the dew's dried and if they are too soft/green, let them dry out for a day or so before plunking in the oil.

Okay this is probably TMI-- but good luck.

Oh, wait: Taste the mint: True peppermint (which will have a red stem) tastes like peppermint. Penny royal is strong & rank tasting. I can't find a good web pix of it to send to you but it's typically smaller and lower growing than peppermint.