The Pendulum is an ancient divination tool used as far back as 2000 BC by the Egyptians, Hebrews, Chinese, and many other cultures.
Pendulums are a very simple method of divination, providing only "yes or no" answers. Made from a (usually oblong, or egg-shaped) weight suspended from a string or chain, the end of the chain is held lightly in the fingers, and the question is asked. The pendulum should, within a minute or so, begin to swing in a particular direction, thus giving you the answer to your question.
Any weighted object suspended from a length can serve as a pendulum. A plumber's bob (like the one my family had hanging in the entry hall for years as an art piece), wedding ring, even a button; suspended from a piece of string, embroidery thread, or the finest platinum chain.
You can buy pendulums made for purposes of divination in occult and new age bookstores. You can make your own with a piece of string or chain, and whatever you want to attach to the bottom of it. It should not be very long (ten inches or so - I use my forearm as a measure), and the weight should be heavy enough to pull the string taut as you hold it gently by the end, but not so heavy that it will give you a pain in the arm or hand. If you don't own a pendulum you can make your own out of silk thread and a needle or a necklace with a favorite charm or pendant.
Always cleanse and consecrate your pendulum when you get it (or make it) before its first use. Keep it on your altar, preferably wrapped in some favorite little cloth or pouch. You may want to carry it around with you in your pocket or purse.
Try to keep it wrapped to keep out distracting vibrations, and don't let anyone else use it. Others may ask it questions, but you are always the one who holds it.
You can use it alone, or you can make a nice cloth (or paper) circle, with straight lines running North-South and East-West to hold the pendulum above. (See our example.) This makes tracking the movement (and answers) easier.
Before using the pendulum, you will want to cleanse and tune it. The pendulum will act as an extension of yourself, so it has to be cleansed of foreign or negative energies, and attuned with your own. To do so, hold it under running water, set it out overnight in the moonlight, bury it in the ground, cleanse it with sea salt (depending on the mineral -- some types of stone should never be put in salt), put it in the sunlight for a few hours, smudge it (sage is best), or set it on a quartz cluster for a day or two. Any of these techniques helps clear the pendulum of energies it has accumulated
(If you are wondering if you are "psychic" enough to use a pendulum, the answer is yes, almost anyone can use the pendulum. In my experience, anyone who is mentally healthy, attuned to the cosmos (as pagans invariably are), has or can achieve inner quiet, and is capable of clearing his/her thoughts (as in meditation), can use the pendulum with great success. Even physical illness doesn't necessarily prevent it.
Once the foreign energies are cleansed from your pendulum, you want to imbue it with your own energies. This can be accomplished through an elaborate ceremony of consecration, or just by carrying it in a pocket or on your person (or by holding and meditating on it) for awhile.
When you are ready to work with your pendulum, prepare yourself by sitting quietly and comfortably in a chair at a table. Don't cross your legs or arms, as this can interfere with the reading. Your feet should be touching the earth (even if that is entirely mental because there's a floor or more between you and her). Once in a comfortable posture, do muscle relaxation exercises if you're not experienced at immediate relaxation, otherwise, completely relax. Breathe with slow, deep, regular breaths. Empty your mind of thoughts, let anything that comes in just float on out the other side; don't attach to any of your thoughts, even with the intent of quashing them. (All this, you may have noticed, is the same preparation we make for meditation.) Once you're in a clear, relaxed, meditative state, you can grasp your pendulum and begin work.
To use it, hold the pendulum cord lightly between thumb and forefinger. Most people rest their elbow on the table for stability and to prevent fatigue. First, ask the pendulum what movement indicates "yes." Note that movement (it will be either up and down, or side to side). Now ask what movement indicates "no." (For me it swings back and forth for a "yes" answer and in a circular motion for a "no." However, your pendulum may move differently.) Now you can get started.
Remember to ask your question in a form which is suitably answered with a "yes" or a "no". The query may be aloud or silent. Do not move your hand. The pendulum will move by itself (that is the whole idea). And it is usually true that the more vigorous the motion, the more definitive the answer. Sometimes a weak yet identifiable "yes" or "no" will indicate a need for refinement of the question, sort of like the "warm"/"cold" game many of us played as children.
Don't be too annoyed if you receive no or an unclear answer. Instead, consider the implications: Could the question use rephrasing? Could you be tired and less focused/receptive than is needed? Could you be asking for information you're not entitled to have (yet)?
In any case, I recommend that you write down what each of your pendulum's motions means, partly to remember better but also to reinforce it in your subconscious, strengthening the pattern. If a while passes between each session and the next, you may wish to refresh the exercise from time to time to reinforce it, as well. I also recommend that you spend time before the session formulating your questions.
How does it work? Some say there is a special spirit of the pendulum. Another theory is that the user plugs into the Collective Unconscious, where all knowledge and answers reside. Another: We each tap our own inner wisdom when we concentrate on the pendulum's swing. Or do our own resident spirits help out? Ask your pendulum! I personally believe that pendulums work by allowing your intuitive/subconscious mind to give you the answer to your questions, which in turn moves the pendulum in the direction in which it needs to go.
~from Maat's Book of Shadows