Write an article based on this summary:

Measure the size of your bottle. Calculate the total amount of essential oil you'll need. Find the ratio of your three essential oils. Swirl together your essential oils. Fill the bottle with carrier oil. Store the bottle in a cool, dark place.
Fill your bottle (or bottles) with water nearly to the top, then pour it into a measuring cup. Write down the number of milliliters the bottle holds. Multiply this number by 20 to get an estimate of the number of drops that fit in the bottle.  If you don't have a milliliter measure, 1 US fluid ounce is close to 30 mL. For example, if you plan to make a large batch of 50 mL, your bottle holds 50 mL x 20 drops/mL = 1,000 drops. Adults who plan to use the body oil across a large area of their body should dilute the essential oil to 1%. If you plan to use it as a perfume or for a small area, you can safely try 3 or 5%. For a 1% dilution, multiply the number of drops your bottle holds by 0.01.  For example, if you have a 1,000-drop bottle and plan to dilute to 1%, you'll need 1000 x 0.01 = 10 total drops of essential oil. Expensive essential oils are often sold in diluted form to make them affordable. If the label says it's already 5% diluted, multiply the number of drops by 20 (since 100% ÷ 5% = 20). As a starting point, try 2 parts base note, 1 part middle note, and 2 parts top note. If you're not sure how to calculate that in terms of drops, follow this example:  This ratio uses 5 "parts" total (2 + 1 + 2). There are 10 total drops of essential oil, so to divide it into five parts calculate 10 ÷ 5 = 2 drops per part. 2 parts base note x 2 drops/part = 4 drops base note. 1 part middle note x 2 drops/part = 2 drops middle note. 2 parts top note x 2 drops/part = 4 drops top note. Sometimes the math doesn't work out neatly, and you can't get a perfect ratio. Just get as close as you can. This isn't the only recipe you can use. If you want your middle note to be the centerpiece, you can go as high as a 1:3:1 ratio. Count out the drops of each essential oil according to the calculations you just did. Add these all to a glass bottle, and swirl it around so they mix together. Since all that math was based on the size of the bottle, you don't need to count out the drops. Just fill the bottle up with carrier oil as full as you can. Close the lid tightly and shake for a minute or two to make sure the oils are spread evenly throughout.  If you planned to fill multiple bottles, fill them all with carrier oil and pour them into one larger bottle. Shake to combine, then distribute it among each of the smaller bottles. At this stage you can smell the oil and mix in another drop or two of essential oil to change the characteristics. Remember that adding too much can increase the concentration to levels that irritate the skin. Seal the bottle tightly and place it in a box or on a shelf away from direct sunlight. Essential oils can last up to 2 years, but some citrus essential oils and many carrier oils have a shorter shelf life. To maximize the shelf life, transfer the oil into smaller bottles as you use it so there is never much air trapped in the bottle. Keep it out of reach of children.  Discard the oil if it smells very different than it did fresh, if it thickens, or if it turns cloudy. Refrigerating the oil can help, but it's usually not necessary, and many carrier oils solidify in the fridge. If you do store it here, let the oil warm up to room temperature before using.