We discussed about this, but I don't really see any problem that the pieces of the model can be created in several places. In this case, the clipboard creates a EditorScene from the data in the clipboard, and then use this action with it as an argument. We could have a Template mechanism that reads templates, asks the user for a few data, and then creates a new EditorScene, and add it using this action. Restricting the creation of the pieces of the model to one place is cohort some possibilities, I don't really see how it's error prone. Remember that the pieces of model created outside this action are not part of the model yet. I don't see the benefits of having the creation of new parts of the model centralized.