Wood, Marble, Metal and Rocky shaders to add to your objects.
Install the add-on, select your object and click on any given shader.
Included:     20 wood, 16 marble, 14 metallic, and 18 rocky shaders.
Each category contains a randomizer button, to create your own random shaders.
Each time a button is pressed, you can also modify the selected shader in accordance with your needs, through the Shader Editor.

Here is the complete list...

Wood:
Beech, Birch, Cedar, Cherry, Chestnut,
Ebony, Eucalyptus, Larch, Locust, Mahogany,
Maple, Oak, Olive, Pear, Pistachio,
Pine, Poplar, Rosewood, Spruce, Walnut

Marble:
Blue, Creole, Dark, Etowah,
Green, Grey, Light, Makrana,
Nero, Orange, Pentelic, Pink,
Red, Ruschita, Swirl, Yellow

Metal:
Aluminum, Brass, Bronze, Copper, Electrum,
Gold, Lead, Mined Gold, Mithral, Rough,
Silver, Steel, Rust, Uranium

Rocky:
Andesite, Anthracite, Basalt, Chalk,
Dacite, Diabase, Gneiss, Granite, Ice,
Lapis Lazuli, Obsidian, Quartzite, Salt,
Sand, Schist, Stone, Unakite, Verdite

https://www.youtube.com/watch?v=DWfcaEks9LU

Feel free to use them on your work.
Thank you.