A great article in Yoga Journal talks about these Yantras.
Similar to Mandalas, both seen as sacred and helping one to turn inward and used for healing. According to the article, the practice originates from the use of mantra (sound vibrations) and yantra (visual depictions of the sound vibrations)...
The article, which is worth reading, is in the Aug. 08 issue, called Drawn Inward by Sarah Tomlinson, page 71.
For me, mandalas or yantras... as long as they bring me into that state of centeredness, peace and being in the moment... doesn't matter much what they are called or how it is done.
Although, what I did find interesting in the article was the approach to them. Starting at the top, working clockwise around and towards the center, brings you out of the chattered mind (external world) and into the calm place within. Oh yeah, to live there... to be able to make clear decisons, to be so focused and calm as not to be rattled by someone's opinion. Yeah, that's where I'd like to live. And how does one get there?...... practice, Doreen, practice and patience.
If you go to www.yogajournal.com/yantras you should come to a page with 5 yantras that you can print out and color... thank you YJ :-)