According to one example, there is provided a method of generating three-dimensional objects in a three-dimensional printing system comprising a pair of movable build modules. The method comprises moving a first build module into a build position, executing a 3D print job in the first build module, moving the first build module into a post-build position, performing post-processing operations on the first build module, moving a second build module into the build position, and executing a 3D print job in the second build module.