Yes, you can 3D print with glass now...

Credit: Imagery courtesy of the MIT Media Lab

Researchers at at the MIT Glass Lab (yes, they have a glass lab) have figured out how t0 print molten glass through a nozzle.

As you can imagine, the main challenge here are the extremely high temperatures involved.

Finding a nozzle suitable for printing glass is  complicated, to work it must be made of a material that can both handle high temperatures and resist the glass sticking to it.

Platinum nozzles are used in industry for some glass manufacturing processes, but are very expensive. Instead the lab settled on a custom-made nozzle made of aluminum oxide.
The machine prints soda lime glass, a family of glasses used in everything from water glasses to windows. But glasses like Pyrex could in principle be printed this way too, albeit at much higher temperatures.

The technology is still in its nascent stage, but if you could, what would you print out of glass?