One of the most impressive applications of Mass-stream technology is the Artificial Planet, actually a kind of Supramundane world suspended above an artificial black hole.
Using accelerated streams of projectiles or particles to either transfer momentum or even support a large structure.
At its upper limits the system can move a planet or even a star in a time span of decades. Another application is in the construction of supra-planetary habitat shells around gas giants or even stars at a level where the underbody generates gravity equal to 1g. Or in building an orbital ring around a planet and using it to support short (approx. 400-800km) skyhooks to provide ground to orbit travel. Or in setting up a network of mass streams to provide rapid transit for vehicles around a solar system. The vehicles magnetically couple to the stream and "ride" it.
Despite the apparent vulnerability of the system to possible power failures, it is quite safe and reliable. Mass stream technology is widely employed in the MPA. Often the sheer engineering beauty of a Lofstrom loop or a mass driver fountain to their aesthetic encourages them to build it.
The most common forms of mass streams are simple iron pellets, although some systems employ more unusual masses. The interstellar catapult mass driver, suitably adapted, makes a perfect catch/throw system for such streams.