Stable zero-valent metal compositions and methods of making and using these compositions are provided. The structure can be, for example, a metal-insulator-metal capacitor, an antifuse, and the like. A door cover is attached to the housing body, and the door cover includes a second part adapted to face the first part when the door cover is closed, thereby forming the part of the first transporting path together with the first part. The avoids substantial dirtying of the transport paths that the powder containers are transported on, thereby eliminating the need for cleaning when the coating material is changed, especially when the coating powder is changed.