Which god forged the armor of Achilles at the request of Thetis?

Hephaestus forged Achilles’ armor at the request of Thetis.

In the Iliad, Achilles’ original armor has been taken by Hector after Hector kills Patroclus, who had been wearing it in battle. Grieving and furious, Achilles is ready to return to the fighting, but he has no armor. His divine mother, Thetis, goes to Hephaestus, the Olympian god of fire, metalworking, and craftsmanship, and asks him to create a replacement set.

Hephaestus makes a helmet, breastplate, greaves, and other weapons. His greatest creation is the decorated shield, whose scenes depict the cosmos and many aspects of human life: cities at peace and war, farming, dancing, legal disputes, and celebrations. The shield turns Achilles’ equipment into a miniature image of the ordered world.

Thetis brings the new armor to Achilles, who uses it in his renewed assault on the Trojans and eventually kills Hector. Apollo, Ares, and Zeus are also major gods in the Trojan War, which makes them plausible distractors, but they are not the divine smith who manufactures Achilles’ replacement armor.