2015.03.05 Garry's Mod update brought a good feature with overriding submaterials.
This is a simple tool to use it.
Duplicator supported.
Usage: select index, select material, apply tool. Right click to revert.
You can copy current material with selected index from model by Reload.
Models with multiple skins can have different set of materials for each skin (other indexes), e.g. same part of model with skin 1 can have material 0, but in skin 2 it will have material 3.
Now with HUD, better usability, and can change global material.
Still BETA, if you see error or want a feature say it.
PS: this is my first working addon, can have bugs...
