Here is the main pack with all those links to original blog posts and tableau public items where other people have done the hard work for us.
Please respect and acknowledge their work.
Awesome presentation david tanner
Great simple example of how to get started with custom polygons and showing some of the tricks that might get people stuck (things upside down)
Also Thanks to Christine Tham who being more organised than I, has a Tableau Public profile. check it out
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