MAGIC PAINT PALETTE by Ickle Pickle
Not a routine by itself, but a magical prop you can use with many other coloring effects to enhance the routine.
The apparatus comprises of what appears to be a regular wooden artist's Palette, with six blobs of paint in different colors.
Just wave the Palette, and the colors vanish, leaving six white (blank) spots in their place.
You can also do this in reverse, having the colors reappear in place of the blank spots.