HP will indeed cover a multitude of of materials. However, Prof. Stephen Hoskins invention is dealing with a new ceramic material.
HP develops a 3D printer which separates printing of the product's core and product's shell. The core is made of a strong material using a certain binder while the shell is made of a different material using an aquaous binder. By separating core from shell, they get a solid product with a smooth multicolor shell .