Someone told me that the common add-in they were using to make transition between 2 elements was discontinued in Revit 2018. So I made mine I’ve been surprised about how easy and short it is : with rpw.db.Transaction(“Create transition”): doc.Create.NewTransitionFitting(connector1, connector2) So the only thing you need is to prompt user to pick 2 elements … Continue reading [pyRevitMEP] Transition between 2 elements