When you need more then base slot used, or need change from the vanilla skin.
To replace a default animation with a new one.
How to merge meshes together
Changing the location of your mod.
Installing mods will in-game, can install both TTMPS/PMPs
https://github.com/goatcorp/FFXIVQuickLauncher Add ons used through Quick Launcher
The resizing of a model to another size.
Installing/creating TTMPS only, along with mod editor
Applying the color and surface properties to the model