It's a pretty straightforward, the same technique that's used industrially for most common ceramic production. I 3D print mold positives that then get cast in plaster. That plaster is used as part of a 'slipcasting' process:

https://en.wikipedia.org/wiki/Slipcasting

> How do you cure/fire your ceramics?

I'm using standard high-fire (cone 10) ceramic slips that I mix from raw powder. They are fired to ~1300 C in a small electric kiln (although it's a particularly well insulated one so it can go all the way to cone 10 without too much trouble).