Great tutorial. I've always wanted to do that. The pictures make it easy to follow, but some of the terms are not quite right. You start with an "octagon" in the center. It has eight sides, hence the "octo", a prefix meaning eight. A hexagon has six sides.
Later, you say to add HST's. Those are half square triangles, and are really a square made up of two triangles. I always found that term hard to understand. So what you are adding are just triangles in several different places.
I don't want to make you feel bad, but it's nice to know the correct terms. Please look them up so you know for sure.
Again, thanks for the beautiful work. Keep it up.