Thule droid factories were in use by the Separatist on the planet Thule throughout the Battle of Thule. They were capable of rapidly assembling AATs, Heavy Artillery Guns, spider walkers, and Ground Armored Tanks.
These factories were heavily armored, capable of emerging unscathed from the firepower of a TX-130 Saber-class fighter tank. Any craft assembled were capable of being deployed from one of two of its bay doors in a matter of seconds. Some factories were protected by tower laser turrets.
During the battle of Thule, they supplemented Separatist forces by deploying numerous amounts of tanks against the clone forces. Jedi Master Obi-Wan Kenobi encountered several of these factories during the second phase of the battle, in which he was tasked with eliminating Energy farms protecting a Separatist Command Installation.