i’m also probing from this side…
but here is the shader you asked sequins.blend (1.87 MB), and i’ve forgot to post it before…
the magenta nodes are previous to my rotation2tangent, just to know.
basically i’ve splitted up the UV map in to tiny little pieces, each has a circular gradient as as mask, a radial gradient as a rotation map, and a noise gradient that is rounded ( in osl i’d use floor(), but here i needed to add 0.5) to make a variation in the normals of each sequin. the rest is quite trivial.