Abstract: A 3D printing apparatus is disclosed herein. The apparatus comprises a container, a build material extraction module, an energy source and a controller. The container is to receive a build volume comprising portions in which an un-cured thermally curable binder has been applied to define a 3D object to be generated and portions on which no binder has been applied. The build material extraction module is to remove part of the build material on which no binder has been applied. The energy source to heat the contents of the container. And the controller is to control the build material extraction module to remove part of the build material on which no binder has been applied; and control the energy source to heat the build material to thermally cure any binder in the container.