I suspect that this would not be something amenable to handmaking; but I am very curious whether there’s anything in the Journal of Nonlinear Optics and Thin Films are Clearly Witchcraft With Harder Math that could be adapted to create such a remapping.
Looks like you can get up to pentaband bandpass filters as off-the-shelf(but not inexpensive) items; not sure if that’s something that can be scaled up; and also not sure if it would be sufficient given all the “lol, you fell for that lie about color being a relatively well behaved frequency” stuff that comes up in considerations of color theory.
