Pedantic note: footnote 1 (supporting the statement that there's nontrivial mathematics behind circle packings) links to two Wikipedia pages, for "Circle packing" and "Circle packing theorem"; the first of those is actually completely irrelevant because it's about how densely you can pack fixed-size circles into a given space, a topic that turns out to have basically nothing to do with the sort of circle packing that's actually relevant to the article.
(Thurston should really have used a different term. "Circle tiling", perhaps.)
(Thurston should really have used a different term. "Circle tiling", perhaps.)