I am glad someone revived this older post regarding the Zig Zag Illusion, as I have named it. And, yes, I know that isn't right. lol
I had forgotten how truly amazing this quilt is. I did notice that Donna Jordan's illusion quilt has longer angles than the original and she uses the 60 degree ruler. The angles in the instructions from the Retalhomania website will probably produce the same angles as the original picture of the quilt. I haven't tried either, but am sure thinking about it.
Now I am really wondering if gigagray ever got her quilt completed. I'll have to go look at her posts.
I did find a posting gigi made with this quilt made by her friend. It looks to be the 60 degree wedges.
https://b-quilts.com/blog/?p=4878