Multi-draggable dropzone

I am looking to create a pivot-query builder, where a user can drag a field into a "values" section. When the user has dragged the field and would like to drop it into the Values section, I would like to create multiple drop zones so that they can choose with type of aggregation calculation they would like to do. For example:

Are there any javascript libraries or demos that would be able to do this or show an example demo of a similar feature (or even a site reference that does something similar to this?)