Abstract: The freeze casting process for preparing a green shaped article such as a biocompatible bioceramic prosthesis or implant, comprises: a) providing a substrate at an initial predetermined spacing from one or more liquid dispensing outlets; b) writing a predetermined amount of a liquid formulation from at least one of the outlets onto the substrate, the formulation comprising: 8 to 99.99% by weight of a liquid sol comprising a liquid carrier and from 5 to 50% by weight, based on the weight of the carrier, of colloidally dispersed nanoparticles having a mean particle size in the range 0.25 to 100 nm; 92 to 0% by weight of a mineral powder having a mean particle size greater than 0.1 micron, and 0.