By now, the ContactEditor app contains several libraries/subpackages. In the RDVBA Code Explorer, I place subpackages either in the project root (e.g., SecureADODB or Storage Library) or under the virtual Common folder (e.g., Guard and Logger).

On disk, I have the Project folder next to my host file (Excel Workbook), which contains all code modules and folder hierarchy matching the virtual folder hierarchy. Assets\Diagrams folder contains documentation diagrams in several formats. Usually, I create originals in yEd-desktop, save them in the native format, and export them as .eps files. Then I open .eps files in Adobe Illustrator, remove the white background, and save them as .ai, .svg, and .jpg/.png. The Library folder contains additional files used by the libraries organized in subfolders named after libraries.