I’m currently rigging Aerilyn and am finished with her hat for now. I’ll move on from it since it requires other parts of the rig to be done, like her body.
It has IK and FK switching and the same wave mechanism as Striae Alis’ skirt. I intend on using it again on robe and skirt.
If you’d like to make something like this, you’ll need some bones, drivers and a lot of patience 
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It was made by parenting the master FK controller to a mechanism bone that has the drivers to control its Euler rotations X (“curling”) and Y (twisting), with the rotation mode ZYX
Since there are 16 bones, there needs to be 32 drivers, 2 in each bone. You can copy the drivers to all the bones, but all of them have to be edited manually since the index of each bone is part of the wavy effect and it has to be different on every bone
These are the expressions I used for the X and Y rotations
If you want to copy/paste:
X:
A * sin(2 * pi * f * t + phi * index) + offset
Y:
A * -cos(2 * pi * f * t + phi * index)