As I mentioned before, the pendulum is the easiest of tools to make. And, even better, it is useful for more than just yes/no questions. It can be used for finding water. Or every water line in your yard. It can indicate precious metals or the gender of an unborn child. Pendulums can indicate the future, contact spirits, delve into the past, determine which ingredients to use in a spell, or, my favorite, find ley lines.
I suppose there are Witches who can merely feel the veins of the Earth pulsing beneath their feet. I am not one of them. I usually like a place, feel a connection to a place, and later discover the ley lines crisscrossing in all directions. Sometimes I don't notice anything at all. I have a ley line in my backyard near the shed and I didn't know until I explored with the pendulum. After I find the lines, I can tap them. Most leave me feeling intoxicated. If you would like some visual clues for lines of power, look for forked trees, standing stones (the bigger the better), and animal paths. Sometimes plants are more lush and green in ley lines and sometimes nothing really grows in the spot. I don't really have an answer for this. I've heard ley lines are destructive and I've found many to be pleasant and healing. I guess having too much energy is just as bad as not enough. I tend to think of ley lines as being like water- a little trickle through the woods does no harm, a flood destroys too much. I encourage you to find your own lines and form your own opinions about them. Some say ley lines are dragon energy and some think it is the naturally occurring energy of the Earth. I think it could be either or neither.