1.MSVS new class library
2.References (minimum):
§System.dll
§RevitAPI.dll
§RevitAPIUI
3.Namespaces (minimum): (*)
§Autodesk.Revit.DB
§Autodesk.Revit.UI
§Autodesk.Revit.ApplicationServices
§Autodesk.Revit.Attributes
4.Implement IExternalCommand and Execute()
method
5.Register with an “add-in manifest” file
§(*) if you use VB.NET, set namespaces in
project properties