Listr.lol can do that for you. For the moment, you can merge your follow list with a newly created list. Then remove the uncool kids and keep only the cool kids. That list will show up in Amethyst. I have one I named test that I made that way. If you look at my npub in listr you'll see it.  nostr.fmt.wiz.biz 

 Thanks, that's awesome. I'll check it out!