There’s a market, albeit a small one, for a variety of ferrule colors if you can come up with something.
I think you’d be better off sticking to only a few colors and see if you can come up with a durable, stain
resistant ferrule that has the best compression properties, durability and appearance. Ivory ferrules are
the best, IMO, but are becoming very expensive and harder to obtain. A substitute is needed and what
are the options? Then see if you can come up with something better or at least different but never inferior.
Presuming you were successful, don’t embark on a making a large variety of colors but rather a select few.
You could become a huge success since cue makers aren’t looking to be innovators & just use the best stuff.