house of kolor carries an "iridesent" powder additive for paint. its not a powder for powder coating i dont think. actually who knows maybe you can add to baking powders. you might have just created a new trend.
anyways go to coastairbrush.com they have every thing you would ever want. or try innate.com or autobodysupply.com
they say the additive glows for approx. 45 min. and you can get different colors.
bondo