The Merriam-Webster dictionary defines art as: the conscious use of skill and creative imagination especially in the production of aesthetic objects; also : works so produced b (1) : fine arts (2) : one of the fine arts (3) : a graphic art. Such an open-ended definition leaves the skill and creative imagination aspects up to the interpretation of the individual artist. So long as it falls under the umbrella of aesthetic objects it can be considered a work of art.
For instance a young artist uses a new material for his latest painting and is criticized as not being a ‘proper’ artist simply because he has not followed any of the predetermined doctrines of what constitutes a work of art. In actuality he has used art in its truest sense, as a form of self-expression which adheres to no doctrines. As a result regardless of the materials or methods this person used a physical work was created from their creative imagination by employing their skill as an artisan. It meets the criteria mentioned earlier of falling under the umbrella of an aesthetic object and therefore it can be considered a work of art.
Art can not be categorized or labeled for it is a form of self-expression which is as individual as the artist creating it. There exist many predetermined doctrines of what constitutes a work of art that try to do this. They are just that predetermined being created by those who came before, and may not necessarily fit your personality. So do not be afraid to break the molds and reforge them as you see fit.