So the website is pretty crappy at giving a simple summary. Nature's video is better: https://www.youtube.com/watch?v=uBMB4FNoYz4 https://www.youtube.com/watch?

So the website is pretty crappy at giving a simple summary. Nature's video is better: https://www.youtube.com/watch?v=uBMB4FNoYz4 https://www.youtube.com/watch?v=uBMB4FNoYz4 TL;DW: they sell glass powder that's mixed with a polymer binder. You can buy it as a liquid or solid. It can be cut/machined as a solid, cast or 3d printed as a liquid, and there's versions that set from liquid to solid with UV exposure. Final processing in a kiln burns away the binder and melds the glass powder together, forming the final object.