After a lot of effort, I have finally got the pattern right! I’m sure I’ve made more of a meal of this than was really necessary, but still. Here are some random scribbles from the last stages of the design/analysis:
All this led to this basic design of the unit cell:
Which actually looks like it is meant to. The colour scheme may have been influenced by me watching Dr Strange 2, which also has some Islamic designs in it. Specifically the one in the good book dimension (or whatever it was).
So far so good, but then I had to draw and paint it, which worked out well:
Very colourful! The 70 degree pattern from before is maybe less obvious due to the rotation, but it is definitely there.
So the final item can be found on Etsy.