Bioceramics like hydroxyapatite (HA) and tricalcium phosphate (TCP) are commonly used as artificial implants due to their remarkable ability to significantly promote bone ingrowth and activate natural bone cells. However, their relatively low mechanical properties limit their application to small bone defects in areas of minimal mechanical stress. In contrast to HA and TCP, zirconia is also a bioceramic which possesses exceptional mechanical properties, making it suitable for areas of high mechanical stress. However, zirconia is bioinert and lacks the ability to enhance bone ingrowth and activate natural bone cells. A hybrid part that consists of two different bioceramic materials would combine the advantageous properties of both. Our manufacturing process is digital light processing based vat photopolymerisation and subsequent thermal post-processing produces bioceramic parts characterised by high density with high resolution (<40 µm). We implemented a process where the parts are processed on a single-material machine and then joined during thermal post-processing. For our sinter-joining experiments, we chose a ring-in-ring design where the outer and inner ring each consisting of a different ceramic material. First, both ceramic materials are thermally treated to remove the organic binder. Second, the inner ring optionally undergoes a pre-sintering step to reduce its size to fit inside the outer ring. Third, the sinter-joining process takes place during the final co-sintering step, in which the materials that are then combined are subjected to the maximum sintering temperature. We use the different shrinkage behaviour of the ceramic materials to achieve a press fit between the rings. To establish process control, our investigations include parameters such as varying pre-sintering temperatures and different co-sintering temperatures and profiles. We also investigate parts with a fine surface texture at the interface. Acknowledgment: CD Research Association, BMDW, National foundation for Research, Technology & Development, Austrian Cluster for Tissue Regeneration