Creating Feature Line from Polyline 3D With Python

I’m getting an error that “feature line cannot be created from entity geometry” using the FeatureLine.Create(String, ObjectId, SiteId) method. What I don’t understand is how Polyline3D.ObjectID returns a list of entity objectIds. Anyone know how I can get the object id of the Polyline itself?

Can you share the dynamo file

I think the 3dpolyline should be made
Then turn it into a feature line

Make line 47 to last code