The Revit Model Builder add-in acts as a layer between the Revit modeling environment, including the Family Editor, and an Excel session. (The Revit environment can include Vasari; however, this has not been tested.)
The Excel file creates a bridge to other applications. There is no restriction on these other applications since the Model Builder is only aware of the Excel file. Most of the work to date has been done with data generated from either Rhino-Grasshopper or a special C# Model Builder Tool which is a Windows program that serves as a template for custom computational projects. Some work has been prototyped in Process and there are discussions about using AutoCAD or other applications. Whichever application is used, it must be customized to create the Excel output based on its own geometry or other algorithm.
The primary workflow is for one of these applications to output an Excel worksheet that follows the conventions described in the next section. Then, from an open Revit session, the Model Builder tool reads the Excel data and creates new geometry in Revit.
A secondary workflow is to create geometry in Revit, and then use the Model Builder to export data to an Excel worksheet. This is useful as a means of creating sample data, which can be edited and then imported to generate new geometry. It can also be used as a way of transferring geometry from Revit objects as drafting or model lines into the Family Editor or another view.