Put gloves on to handle the arnica flowers. Order them dried online if you can't find them locally. The plant's blooms are the only parts used for the arnica oil.
Grind the arnica with a pestle and mortar, electric blender or food processor.
Transfer the arnica flowers to a glass container that has a lid. A mason jar works fine.
Multiply the amount of arnica flowers you used times five. If you have 8 ounces of dried blooms, for example, the result of your math problem is 40 ounces.
Measure an amount of your favorite vegetable or body oil equal to five times the amount of arnica flowers you put in the jar. Oil possibilities include jojoba, olive, peanut and grape seed.
Pour the oil into the container with the arnica flowers and close the lid. Let the blend sit undisturbed for one month.
Rub a small amount of arnica flower oil on your skin next time you have a muscle ache or a bruise. Don't use it on open wounds. If your skin reacts, wash the oil off and don't use it again.