Armory

The Armory is a technology that lets you build more advanced weapons such as EMP rockets and flak, compared to the simple guns available at the start of the game. These are strong defensive and supporting options, so the Armory tends to be a solid choice in competitive multiplayer.

They cost the same as the Workshop: 400 metal and 2000 energy to construct and take about a minute to construct. Like the Workshop, the Armory enable the construction of a Factory and/or Munitions Plant for heavy weapons.

Source

 * Tons of Guns - Weapon Guide By EarthWork Blammo