You can order a correct Sri Yantra online
For quite sometime I have been observing the many multi coloured sri yantra pictures published in the various websites and tantra books.
While one is free to visualize HER as one wants, being a sri vidya upasaka I thought of making a sri chakra with the right colours as described in the various scriptures. The following is the outcome of my study of several tantrik scriptures, mantra mahodadhi and also the writings of Sri Amritananda.
1st Avarana the outer square with three lines and 4 gates is brown. The outer line is white (though the colour of the 10 deities here is like molten gold), the middle line is orange red like the rising sun and the inner line is yellow like the colour of butter.
2nd Avarana the 16 petal lotus is pink like lotus flower.
3rd Avarana the 8 petal lotus is red – the colour of Bandhuka flowers.
4th Avarana the 14 cornered triangle is colour green like the colour of glow worms.
5th Avarana the outer 10 corners triangle is red like Japakusuma flowers.
6th Avarana the inner 10 corners triangle is colour blue (though the deities here have the lusture of 1000 rising suns).
7th Avarana the 8 corners triangle is colour red like Dadini flowers.
8.The innermosst triangle is white.
9.The Bindu the central point is red like Sindoor.
I made the above picture by colouring the 9 avaranas accordingly. The background colours are of course to give a visual effect.
The Sriyantra of Devi is a great geometric design. It takes a lot of geometric perfection to get it perfect. When it is perfect, if you draw 2 lines bisecting the top and side both will cross at the central bindu and will also cut through the tips of the triangles and padmadalas on their path as can be seen in this pic bellow. This is designed as per the instructions given by the great Adi Shankaracharya to get the geometry right to draw the correct Sriyantra. 
