I think it would make more sense to force the user to create the list first, rather than create the elements under it. You can name the CTA "Create a list" if none exists.
Then, once at least one list exists, you can keep your "Create a new list" inside the drop down at the end like you did on your mockup.
Then the "Add an element" could be called "Add a metal" so the user knows what he is adding.
Then the fact that a list has been modified should be transparent to the user, he shouldn't have to save the list or anything : as soon as he has added a new "element" to the list it should be saved.
For removing "elements" of the list, I think it's easy enough, but I would maybe place it a bit further on the right hand side so that the user doesn't click on it by mistake while manipulating the drop down menu.