• Add a button to creative inventory:
  #19
• Add a button and a hot key for swapping cosmetic slots: curseforge comment
• Add cosmetic slots to Baubles just for specific baubles' look: curseforge comment

I might be describing this horribly but; make it to where this mod can be used on a server that doesn't have the mod, that way it effects the user and others on the server who do have the mod. An example of a mod that does this is MorePlayerModels. The players who do not have the mod are not effected and see no change, however, all players whom do have the mod on a server are able to see the changes that they make to themselves and that others make to their player models