For the fabrication of patient individual bone replacement scaffolds using rapid prototyping (RP) technology, materials with properties adapted to the 3D printing process are needed. First of all the granulate properties of the building material have to match certain specifications concerning particle size and morphology. To fulfil these demands in laboratory scale a commercial fluidized bed granulator was modified to match the specific needs. The changes were tested spraying a sample granulate for the fabrication of synthetic bone grafts. This granulate could successfully be processed in the 3D printer.