Is there any palette editor for BUILD? All game developer teams made their custom palettes for their games, so I think it's possible to make custom palettes. But I can't imagine how can I do that.
Kyoufu Kawa at
EditArt can do that by importing an image with the desired palette. Read the EditArt docs for more info.
JonoF at
Or, if you can get the palette into Paint Shop Pro format, my old tool for palette manipulation can import it: http://jonof.edgenetwork.org/index.php?p=bcs