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+.

[1] https://www.nobula3d.com/

[2] https://ethz.ch/en/news-and-events/eth-news/news/2019/11/gla...

[3] https://www.glassomer.com/products/glass-3d-printing.html