R2C4D is a plugin set developed by IT Serwis that offers easy data transfer between Autodesk Revit and Cinema 4D. It maintains Revit hierarchies as well as assigned Material IDs, and also allows to bring new changes made to the original Revit scene to Cinema 4D using an update function. More on R2C4D’s website.
This plug-in is supposedly really amazing, however, this company took our money, refused to provide the final product, and is now unreachable by email or phone for help. Stay away. Do not purchase.