And you can't shoot them into space with a mass driver, nor can you build them in space with a mass driver, nor can you really economically effectively chemically propel them into space (except for the first one).
So, IMO, mass drivers lead no where, except to drive refined ingots of ore into space, (and we already have ore here on earth).
Huh? All I said was the gravity well of the moon allows for using mass drivers to propel material into lunar orbit. This is considerably cheaper that what we do today. You can build you "parts" on the lunar surface. Of course, this would require a considerable lunar colony and manufacturing infrastructure. OTHO, energy is cheap. Solar would do quite nicely up there.
Anti-gravity, warp drives, etc. are pipe dreams. So lets put our money where it actually will get us somewhere.