A 3D printing apparatus is disclosed herein. The 3D printing apparatus comprises a build compartment defining a build chamber within which a 3D object is to be generated; and a non-powered platform, moveable within the build chamber, comprising a platform drive interface to engage with an external drive mechanism to cause the platform to move. The 3D printing apparatus further comprises a powder compartment located laterally adjacent to the build compartment, within which build material is to be stored for use in the generation of the 3D object. The 3D printing apparatus also comprises a locking interface to couple the 3D printing apparatus with an external hosting device.