In retrospect, it's obvious that you should be able to 3D print in glass. It's a liquid when heated, can be poured fairly precisely, and solidifies nicely.
The GIF below gives you a bit of a hint of what it looks like, but if you click through there's an entire video of watching this device in action, and seeing the things it makes. It's strangely hypnotic.
Now I'm just waiting to see future versions which can also blow the glass, not just deposit it...
via +Adam Liss
and +Betsy McCall