What's the difference between a god you can build and the God who builds everything?
Isaiah uses the creation of idols to highlight the fundamental difference between the gods of human making and the true God. The idols are made by human hands, from materials humans possess. They are crafted by goldsmiths, shaped according to human design and desire.
In stark contrast, the true God is the uncreated Creator. He doesn't need to be made; He is. He is the one who sustains and carries His people, as the surrounding verses emphasize. The idols are passive, inert objects that cannot act, speak, or save. They are the product of human labor and expense, yet they are treated with divine worship. This illustrates the profound irony and delusion of idolatry – worshipping the work of one's own hands, or the hands of another, instead of the One who is truly worthy of all worship.