How can I set a selection-sphere in the editor

I have a gameobject in my unity editor. It only has one component, which adds an "editor preview" as child-object. The child object has `.hideFlags = HideFlags.NotEditable | HideFlags.DontSave | HideFlags.HideInHierarchy | HideFlags.HideInHierarchy;` set. ### Problem My object is not selectable in the scene view. Can I do something like "AddSelectionCollider()" ??