That kind of surprises me, since then I'd figure that somebody would be making t...

That kind of surprises me, since then I'd figure that somebody would be making the equivalent of a reprap that puts out glass filament like this 3D glass printer [1] or various glass resin methods ([2] and [3]) Just with some kind of inline laser processing, or post deposition modification. Most of those use UV or lasers anyways. The methods mentioned don't seem like those should cost $20,000/unit unless the unit's 1km+.