Management system to control a 3D printing system that includes at least one 3D printer, at least one build unit in which 3D objects can be generated by the 3D printer, and at least one material processing unit in which processing operations can be performed on the build unit. The management system comprises a processor to obtain status data from at least some of the elements of the 3D printing system, to obtain data relating to a print job to be printed, to determine, from the obtained data, a schedule of operations to be performed by elements of the 3D printing system and to generate control data to allow enforcement of the determined schedule.