You will need to first identify how you wish to use your pendulum. If you are dowsing the pendulum with reference of indicators on a chart, then you need accuracy. You will need to understand that the dowsing technique is based on the channeled signals translated as subtle energies that is intepreted by your subconcious. This signal is then transferred via your hand which is holding the pendulum to an accurate answer. Thus, you will need a light weight pendulum. Ensure the tail till the tip of the pendulum is aligned.
(Note: This article is not meant to give you a crash course on pendulum dowsing, a hands on practical session is recommended for better result)
Can pendulum be of any material instead of crystal? Yes, anything that could mimic a dowsing object is suitable to be used as a pendulum. When you dowse, you are not channeling the object, you are channeling the guides. The difference is, when you perform the clearing process, the crystal will then share it's healing properties to rid, restore, heal and perform any functions suitable, thus optimizing the healing process.
On the other hand, for experience channeller you may be using your pendulum differently. If you are channeling directly and performing the clearing and healing process by simply encircling the pendulum clockwise, a comprehensive crystal pendulum on the right is awesome. The designer of this pendulum, Jerry recommends you to hold each crystal at its different length to perform different healing or on each chakra. So use your creativity... pick the crystals, string them and make an awesome pendulum.