Fortunately, a friend of mine (Starbucks employee) told me how to make them. It's very simple, and cheap!
Before we start, you need to know that Starbucks uses espresso coffee in their frappuccinos. If you really want to be authentic you'll use an espresso maker.
About a year ago I heard about the AeroPress Coffee & Espresso maker on Lifehacker.com and it was one of the best purchases I've ever made. After trying it you will never go back to a drip coffee maker again (It's only $26, and you will be happy you bought it). Check it out on Amazon here.
But, if you decide to stick with a drip coffee maker and you don't have any espresso on hand, you can just make double strength coffee. There are two ways to do that:
#1 (The least effective) Is obviously to use twice the recommended amount of coffee grounds for the amount of water used. This will give you a slightly stronger coffee.
#2 (The most effective) Is to run your coffee through the coffee maker twice. Yes, I said that. It won't harm your coffee maker, and it will give you some mighty strong coffee. Just make sure you run some clean water through the coffee maker after you're finished, to flush out any coffee that might sit in the lines.
NOTE: If you appreciate this Instructables, and you use it to save you money... Please buy me a coffee. It's only $1, and I appreciate it. The coffee helps get my mind going so I can write more Instructables.
Step 1: Let's Make A Frappuccino
1/2 cup espresso or double strength coffee
2½ cups of low fat milk (Starbucks uses 2 percent)
1/4 cup granulated sugar
1/2 tablespoon dry pectin*
* Pectin is used in canning as a natural thickening agent, it is used to give the frappuccino the "smooth" texture. It is the "secret ingredient" in the drink. You can buy this in any grocery store under the name Ball® Original Fruit Pectin.
Combine all of the ingredients in a pitcher or covered container. Stir until sugar is dissolved. Chill and serve cold.
To make the "Mocha" variety, add a half-teaspoon of cocoa powder to the mixture.
To make the "Caramel" variety, add a tablespoon of Torani Caramel Syrup to the mixture.
To make the "Vanilla" variety, add a tablespoon of Torani Vanilla Syrup to the mixture.
To make the "Mint Mocha" variety, add a tablespoon of Torani Peppermint Syrup to the mixture.
You can make just about any additional flavor imaginable with the dozens of Torani Syrups available.
Note: When you add the dry pectin, sprinkle it carefully and stir it in quickly as it will immediately start to lump together, and a lump in your coffee is not what you want. If done carefully, you can mix it in without creating any.