Buildings are structures and mechanisms that can be created by an engineer. There are three types of TF2 engineer buildings: Sentry Gun, Dispenser, and Teleport. Every building has its own abilities: sentry gun - damage, dispenser - heal, teleport - teleportation. Each building has health-points, yet enemy characters can destroy it. To build, repair, and upgrade buildings, engineers need to have metal. But you don't need metal to find all the skins for your buildings on DMarket.