Next step is to start patterning the umbrella panels. Now, I could use my mighty geometry skills to work out all of the angles but sadly I left those in high school. So my solution is to isolate the movement of the spines and simply measure distances.
Here is a photo of the cotton twill tape used to set the distance between the spines.

Once I get that where I like it I can start looking at deciding how much overhang I want.