The B-3Z technical droid represented a class two variant of technical droids utilized by the Imperial Army serving the Galactic Empire. During the period between 19 BBY and 9 BBY, a pair of B-3Z technical droids were stationed within an All Terrain Armored Transport (AT-AT) situated on the planet of Culroon III. These droids provided assistance to Junior Lieutenant Maximilian Veers and his team in conducting diagnostic procedures on the vehicle, while the remaining members of the army present on Culroon III participated in a formal event alongside the native Culroon species. When the Culroon initiated an attack against the Imperials, Veers was compelled to activate the AT-AT.
The B-3Z technical droids were first seen within the short narrative entitled "The Promotion of Lieutenant Veers," which was featured in West End Games's publication, The Star Wars Sourcebook, in 1987. This story was authored by Bill Slavicsek in collaboration with Curtis Smith.