Forges are base structures used for building, crafting and repairing metal items. They require a roof and 70% cover to be usable. Repairing items does not cost any resources.
Upgrading a forge enables additional crafting recipes and higher upgrade levels for items. Each level also increases the build radius by three meters, up to a maximum of 38 meters. A forge can be upgraded up to level seven by building following structures near it: