Cold issostatic compaction
Ceramic material is put into a rubber mold and then into a chamber filled with water and pressurized to about 20,000psi and held for 5 to 10 minutes..
After parts are removed from the mold they can be green machined to approximate dimensions before sintering.
After sintering, if dimensional tolerance is critical, diamond tooling or ultrasonic machining can be used to complete the parts.