Yantras

  A Yantra is a symbolic diagrammatic representation of a Deity, or parts of human body, various aspects of life - both spiritual and material, the shad chakras, the nadi centers etc. Take the above Sri Yantra (Also called Shree Chakra) for example. It represents Devi Lalita Tripura Sundari or Kamakshi Devi or Shodasi Devi or Shakti. The outer 3 lines, called the 1st Avarana, represent her feet, the inside 8 petal lotus, called the 3rd Avarana, represents her nabhi or naval and so on. There are 28 Devies placed in specific places on the 3 lines - or her feet. The other Avaranas also have different Devies placed at different specific locations. While doing Tantrik worship, where each of these Devies are individually worshipped with mantras and by offering flowers or Akshintas etc., it is more convenient to worship a Yantra than a picture or an idol. The same is the case with Hanuman yantra, or Kubera yantra or Navagraha yantra etc. - with variations in deities, numbers, locations and beeja mantras etc. 

In the olden days people used to draw a yantra at the pooja place, on the ground or on a wooden board or metal piece, with rice flour or wheat flour or sindoor. This was very convenient but while doing pooja it can easily get erased. A longer lasting method was to make a yantra by engraving the yantra on a copper or brass plate. The rich class used silver or gold plates. They had to go through all this trouble because in those days there was no paper or printing. The metallic materials are used essentially to enhance the longevity and the visual presentation. In some cases for certain specific purposes yantras made of gold, silver etc are prescribed. Today, for regular normal worship the best is to get a good printed yantra and laminate it.

If the purpose of your buying a yantra is simply to hang it at the pooja place, or wear it, or do a simple worship with a stotra or mantra, then you are better off buying a picture or an idol of that God than a yantra, because, for example, the photo of Lord Shiva is more familiar to you and invokes more bhakti feeling than His yantra. 

However, If you want to do a proper Tantrik worship (which gives quicker and better results), by ritualistically following all the anganyasa, karanyasa, mudra, avahana, pratisthana, offerings, rituals and worship the various places of the yantra with the prescribed beeja mantras, then a yantra is more useful. For proper Tantrik worship you have to do the pratisthana yourself and by following all the rules do a 100,000 times mantra japa within 44 days (one mandala). Normally people do 125,000 times mantra japa in 48 days - the extra number to take care of any mistakes in pronunciation or counting. 

Even if you cannot do a full ritualistic pratisthana etc, at least you must worship 108 times daily with the prescribed mantra.

Now a days a lot of self proclaimed Mantriks, Tantriks and web pundits are promising the sun, moon and the stars to gullible people with all kinds of nonsense.