Prototype was the common designation for a first working model of a new invention.
Davros unveiled the prototype Mark III Travel Machine before 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)