The materials needed for crafting will be acquired primarily through salvaging. Items that the player finds but has no use for can be salvaged and converted into raw materials that can be provided to the Artisans for use in crafting. The crafting materials will take up much less space in the player's inventory than the items themselves, and will be stackable, thereby reducing the frequency that a player will need to return to town to clear out his inventory. Once an item has been salvaged, it is destroyed indefinitely. Salvaging was made capable by the Nephalem Cube but that was changed in development to a service offered by the Blacksmith.
In general, higher-quality items will provide more valuable and rarer salvage than lower-quality items. Only magical items (blue) or higher are salvageable. Below is a list of the currently known crafting materials for each difficulty level which can be found.
Currently used Crafting Materials in Diablo III