1. A system for creating and editing media-based projects for printing products, comprising: a computerized server connected to a data network, the server having access to a memory storing instructions for providing an executable graphical user interface (GUI) accessible by a computer browser and adapted for creating, displaying, editing, publishing, and printing one or more media-based products; at least one data repository residing on the network, the data repository accessible to the server, and storing individual project pages and page assets including at least images and project-related graphics; a print configuration engine executable from the memory, the print configuration engine adapted for rendering media-based projects for printing products; and at least one bi-directional communication channel established between a computing appliance executing a version of the GUI while connected to the network and a server managing the data repository, wherein the GUI enables logical selection, grouping, and sizing of the individual project pages and the page assets, and automatic page population of page assets based on determining a core aspect ratio for the projects based on metadata particular to each page asset including at least size, shape, and orientation, wherein the core aspect ratio comprises two or more output sizes corresponding to a given orientation of the individual project pages, wherein any individual project page having said given orientation does not require any editing of page content before printing in said corresponding two or more output sizes, wherein the core aspect ratio is calculated so as to result in minimal loss of page content during printing of said individual project pages, and wherein the GUI is capable of displaying the project in the two or more output sizes, and wherein the GUI enables an automated process whereby new project pages are dynamically created for printing a new product requiring second page size aspect ratios based on the core aspect ratio of the project, and the size, shape, orientation, and metadata particular to individual page content assets.