A substance’s existence does not ontologically depend on the state of anything beyond the substance. But a typical artifact depends on absences of materials beyond itself. A classic example is a statue that comes into existence when the surrounding marble is removed. The statue’s existence is grounded in part in the absence of the surrounding marble. Similarly, even if a knife blade is made by forging rather than by removal of material, one can destroy the blade by encasing it in a block of steel: the existence of the knife is grounded in part in the absence of surrounding steel.
Thus, it seems, typical artifacts are not substances.
But this argument was too quick. What if the laws of nature are such that the following is true? When the sculptor chips away the surrounding marble to make the Hermes, a non-physical component, a form, of the Hermes comes into existence. That form is united with the Hermes’ matter. And what makes the statue be itself is not the absence of surrounding matter, but the presence of the form. It may be that by the laws of nature the form only comes into existence as a result of the removal of material, but it would be logically possible for the form to come into existence without any removal: the statue causally but not ontologically depends on the absence of surrounding material. God could make the statue within the block of marble, without any removal of material, simply by creating a form for a Hermes-arranged subset of marble molecules.
(One could also have a non-Aristotelian version of this account in terms of Markosian’s brute theory of composition.)
I think the above Aristotelian story is implausible. One reason is that the story conflicts with our intuitions as to the survival conditions for artifacts. A statue is essentially a statue. But the Hermes-shaped bundle of atoms in the block marble, even if distinguished by a metaphysical union with a form, are not a statue. Maybe God could make a form for these atoms, but it wouldn’t be the form of an artifact.