It's the opposite direction, but I'd go with diffraction grating glasses and tune the stage lights for maximum rainbow-ness.

(Diffraction gratings are basically a huge number of tiny parallel lines etched into a transparent medium like glass or film, and split any light into its component wavelengths, so you get rainbow halos around any light source that isn't a single source like red LEDs. Cheap ones on film are a spin-off of holography — it's really easy to get lasers to draw those lines by an interference pattern bouncing off objects — you can get 'em in cardboard frames, like the old red-blue 3d glasses; there was a vogue of selling them at fireworks stands to rainbow up displays. Amazon has them at under $10 for a pack of 25.)