This may be out of scope for this mod, but I figured it would be worth mentioning. In the past, mods like Armourer's Workshop gave players the ability to skin individual pieces of armor, tools, and weapons. This allowed for customized items like that to exist without the need for a special texture pack. Sadly, it seems to have no plans for updating beyond 1.12.2, it's developers have made that clear. Custom Player Models is the next closest thing to Armourer's Workshop for modern versions, it is just missing this key feature.

I am suggesting that some sort of system for applying custom models/skins to these items via something like naming them the name of the model at an anvil, or perhaps some sort of command to apply the skin/model to the item in the player's main hand. This would allow for the item to also keep its texture when given to another player, allowing for players fond of creating custom weapons, tools and armors to make things for their friends without the need to export any files or similar procedures.

Once again, I am not sure if this is out of scope for the mod or not, I just figured it was worth mentioning. I love this mod nonetheless, I just want to see how far it can go!

The issue I find with this method is that armor that kept its shape would be incompatible with other model shapes in Minecraft and doesn't seem to fit the purpose of the mod. I think a better method would be to have armor designed specifically for each model. Barding for a centaur, chestplate for a dwarf, acorn necklace for a fairy, etc. A separate model and texture that could be designed and stored on the cpmmodel. Another more mod-friendly option would be to keep the textures of each armor, but have the modeler specify the model for the armor, stretching the textures as necessary for differing builds. This method would be lighter on cpmmodel size and would be compatible with resource packs and modded armors, like Armourer's Workshop.