I did make some plastic coloured with black mica and purple flip mica that gave some shine but not nearly as good as when brushed on.
Back to the drawing board.
I've done a dozen different batches of black by adding the color shift pearls to the plastic itself without a lot of wow. By far and away the best use of the color shifting [flip mica I'll assume] is to brush it on the body of a black bait, then dip it in clear plastic to seal it up good. The clear dip also amplifies the effects of the pearl. There are some of the color shifting pearls that are developed to go into clear a suspension such as finger nail polish which will then be applied over a base color. These pearls could go into clear plastic and used as a cover dip to get the desired effects from the pearl, or this type of pearl could be brushed over that base color and finished with a clear dip.
Most of the pearls used in plastic simply lose 50% of their ability to "work" because they get lost in plastic color. By brushing the same pearl on the surface of a bait with a high contrast base color [black, very deep green, very deep blue, very deep purple] the reflective nature of the pearl comes to life in a big way because the actual pearl coat is so thin that tons of light can pass thru it going in and is absorbed by the black underneath it. That light is not reflected to pass back thru the pearl like a light base color would do. The pearl coat lets light in and that black base color is sucking light like no tomorrow and that's where the dramatic effects come from. That clear top coat makes the color that much more crazy because the clear is wrapped around the bait and will twist the light that hits the bait because of its thickness. There is basically no thickness to the pearl coat so it doesn't twist the light much. The clear? Quite a bit.
Mike J made some paddletails that used a core done with scale netting and brushed hi lite [I think it was hi lite powder. Maybe Mike will chime in on this] and these were set in the cavities of the paddletail mold and injected with a clear I believe. These baits were outstanding, yet they would have been less so if that clear plastic did not coat the pearl.
Someone mentioned using a heat gun or hair blower to heat up the pearls brushed on the surface of a bait, but if the heat gets out of hand the tails can curl while cooling.