The Great Liberation: Mahanirvana Tantra

Draw a triangle with the Maya Vija within it, and around it two concentric circles (the one outside the other). In the space between the two circumferences of the circles draw in pairs the sixteen filaments, and outside these the eight petals of the lotus, and outside them the Bhu-pura, which should be made of straight lines with four entrances, and be of pleasing appearance.