Most player owned guilds require metals to create stock, in order to make profit. The materials are provided by smelters,
who buy their stock from the players that sell scrap gear in
their shop.

There is a large variety of metal in the realms that are available to these guilds. Here is a list:

Obdurium (rare new material!)
Adamantite
Mithril
Platinum
Gold
Electrum
Silver
Steel
Iron
Copper
Bronze

In addition to these metals, guilds also accept and use leather, cloth and wood.