Prototype was the common designation for a first working model of a new invention.
The first prototype of the Dalek casing was the Mark I Travel Machine, little more than a life support tank with sensory input and voice capacity. (AUDIO: Guilt) Later attempts to create what would later be referred to as the Mark III Travel Machine were initially unsuccessful until a more resource intensive construction was employed. Though operational, this first prototype lacked many features of later Dalek models. (PROSE: Davros Genesis) Davros later unveiled his perfected prototypes to the Kaled Scientific Elite. The Fourth Doctor witnessed this on his mission from the Time Lords to interfere with the creation of the Daleks. These prototype Daleks exterminated the Kaleds, including seemingly Davros himself. Though by that point they were entombed by the Thals, the Daleks survived with their future leader vowing that they would ultimately emerge. (TV: Genesis of the Daleks)
The Master duplicated a stolen Time Ring prototype in a plan to send his agents to assassinate key figures in Earth's history, but was thwarted by James Stevens, who used one of the Time Rings to prevent Lee Harvey Oswald's death, and later to assassinate John F. Kennedy. (PROSE: Who Killed Kennedy)
During the Dalek Invasion of Earth, General Sanchez gave Martha Jones the prototype for Project Indigo, teleport technology salavaged from the Sontarans in the Sontaran invasion of Earth, so she could travel to the Osterhagen Station in Germany. (TV: The Stolen Earth)