Hi,

As Marm said, plaster of Paris will be your best option based on a 3D printed mother mold.
Look at Shapeways for suitable materials for the mother mold, they for example have a wax material used for lost wax casting.
As detail is imperative for these molds, you need to use SLS, SLA or polyjet mother models.
The Smooth-On materials will not resist 1400F but nonetheless are great materials to work with.

I have worked with plaster before for small parts and am planning to use it for larger molds as well.
I would like to know if anyone has experience with large plaster molds and what the drying time is for these molds.
For faster drying times you can use British plaster Herculite 2.

Post pictures and keep the thread alive!