An artist messages varies from artist to artist as each artist will used their own ways to come by an idea. Their choice i material will symbolized different things and it is at the hand of the artist to do so to what is right to him. Each material as its own meaning and a combination can mean something a whole different. Expressing the message relies on the material in which the artist used to come across a message.
Form is actual, three-dimensional shape, though it is often used to describe the illusion of three-dimensionality, as well. Like shape, form can be geometric or organic.