Don't have a juicer?
Having a juicer affords you the most options and creativity, but it isn't necessary to have one to do a juice fast. Only a small amount of juice is actually consumed during a juice fast, the vast majority of your hydration will come from purified water.
These are some options for use without a juicer:
Lemons are easy to squeeze by hand. Use the juice of one lemon in a cup of warm water. A little honey or real maple syrup may be added to make it more palatable. This is much like the Lemonade Diet/Master Cleanse, which is a highly effective fasting routine. Lemons are very cleansing and detoxifying and are known to be helpful in breaking up mucus, which is great for the bowels.
Small citrus juicers are very affordable, some as little as $20. With one of these, you could use oranges, grapefruits, tangerines, lemons, and limes for your juice.
Depending on the time of year and your particular health food store or farmer's market, you may find fresh juices available that aren't pasteurized. In the fall, apple cider (soft, no alcohol) may be available.
You can use green powdered drinks available from health food stores or online.
Make a vegetable broth to use as your "juice". Broth fasting is an acceptable form of fasting, and while it won't deliver the live enzymes that raw juice does, it will have plenty of vitamins, minerals, and electrolytes. Add lots of leafy greens to the broth for the best nutritional punch. In the winter, this type of fast can be very satisfying and warming. Save the strained out vegetables to eat after your fast.