Dynamo refers to a free, open source graphical programming add-in for Autodesk Revit ideal for computational design. This revit add-in facilitates customization of building information workflow. Dynamo expands building information modeling through by integrating the data and logic environment of a graphical algorithm editor.
HyunWoo Kim has provided some useful tips for Revit users that shows how to produce topo cut model automatically through dynamo.