Edge Stitch
Uses: Clothes, Foliage, Mountains, Fields, Samplers
You need one thread for the "pi" π motif. (blue) The small cross stitch, yellow, is worked in another thread and the slanted stitch, black, is a thin metal. The blue stitches should be worked first. This will give you a good foundation for the rest of the stitch.
Although Edge is slow to work, the results are very striking. You may wish to experiment with different threads to see which combination you like best.