Here's a Sri Yantra mandala I designed. Normally there's an error visible at one of the intersections but there's no error. It evolved from the "seed of life" pattern. Some of the steps to getting the first triangle are similar with those used in Hirano's pentagon construction. Actually the triangle that results in no errors base is constructed approximately .55 of the distance between a golden mean based triangle(ie 1/2 base to side 1:phi) and what I call a pi based triangle having a height of 4 and a 1/2 base of .999999pi . To cut a long story short the first triangle results in the error intersection being "open" and the second in it being "closed": so it was logical that "no error" would be somewhere in between.
Heres a some links to images of the design and how its done:
https://plus.google.com/u/0/photos/photo/106786997045225223137/6357042290140922306?icm=false
https://www.geogebra.org/m/UGU7fnKY
https://www.geogebra.org/m/vTQq4qBu
