What did the Israelites make while Moses was on Mount Sinai?

Answer: A golden calf

Aaron made a golden calf and the people worshiped it.

“He took the gold from their hands, and with an engraving tool he fashioned it into a molten calf. And they said, “These, O Israel, are your gods, who brought you up out of the land of Egypt!””— Exodus 32:4 (BSB)