Not sure if I’m missing the point here. But do you mean something like this?
I do quite a lot of proper wreathed hand railing and the geometry can get interesting. Especially because the shaped section of the handrail has to follow the centre line, but unlike this section, it has to stay horizontal laterally.
Often the wreath has to predictably and accurately traverse some interesting lines as below.
David
Edit: I should have said in this case I created a distorted cube and drew sketches on each side for the sweep tool to follow.
