The Infinite Engine was created by Darth Revan from a piece of the Star Forge. He learned that it had far greater potential, where it had the power to create entire galaxies given time. This fragment was later awarded to a number of alien Ongree servants of Revan who were placed as the machine's guardians and were protected in a complex that was equipped with automated turrets as well as assassin droids.
The existence of the complex holding the Infinite Engine was discovered by the Old Sith Empire during the Cold War, and shortly recovered by Agents. IT was studied and was determined that the Engine didn't just feed on the Force energies of the beings near it, but also could operate from energy produced from typical power plants, though this slowed its "growth". Given time it would become a great asset to the Sith Empire, but because it wouldn't be ready for any practical use for war anytime soon, the Engine was place in storage and forgotten.
The Engine would come into the possession of a Lord of the Dark Counsel, who would secret it to Sovereign Forge "Alpha" where it would be installed and under the guidance of Evolve grow over the next few thousands of years.
New Evolve Infinite EnginesEdit
The Sovereign Forge "Alpha" over time became capable of building new Infinite Engines from scratch that would be installed on Harrower-Class Stealth Dreadnaughts and other ships, but this version had several differences from the original. First it wasn't capable of growing any larger then it already was, simply because of that it was limited in what it was able to produce. For one it couldn't produce even a full size fighter in one go. It could produce the parts of the fighter which could then be assembled, or parts needed for maintenance of the host ship.
It also needed more then just energy to make what was requested. These Infinite Engines required raw materials which it could then shape into nearly anything, so long as it had the data needed to make it.
Other Infinite EnginesEdit
Its not currently known if Darth Revan had other Infinite Engines hidden away, or if there are other sources of these devices. But the technology has certainly been mimicked over time, like in the The Foundry, an orbital droid factory able to build droids at a incredible rate.