Methods and apparatus for variable document printing are disclosed in which a graphical user interface is configured to allow user manipulation of layout rules associated with content containers within a template for variable document generation. One method involves creating a layout for a variable data document based upon a template. The method firstly sets at least one container in the template to form the layout, and then establishes at least one constraint associated with each selected one of at least one feature of the container, the establishing including, for each feature, detecting a user instigated selection of the corresponding feature. The layout is then modified to thereby generate the document by placing content into the containers, wherein at least one dimension of the least one container and/or a position of the at least one container in the layout are varied based on a property of the placed content on a condition that each constraint in the layout is satisfied.