Blueprints were detail plans. They were usually made for buildings. Torchwood got hold of the blueprints for the warehouse where the Cash Cow was being held, in order to plan an attack. (TV: Meat)
On Vulcan, a Dalek completed the blueprints for a meteor storm computer in Lesterson's laboratory. (TV: The Power of the Daleks)
In his research of the Doctor and the Time Lords, Ramón Salamander managed to develop a blueprint for a TARDIS control console in his attempts to build his own space-time vessel. (COMIC: The Heralds of Destruction)