If you activate Argent Sphinx’s metalcraft ability, Argent Sphinx will return to the battlefield at the beginning of the next end step no matter how many artifacts you control at that time.

If you activate Argent Sphinx’s metalcraft ability during a turn’s end step, Argent Sphinx will return to the battlefield at the beginning of the following turn’s end step.

If you control an Argent Sphinx owned by another player and activate its ability, Argent Sphinx will return to the battlefield under your control at the beginning of the next end step. You’ll retain control of it indefinitely.