In Shemoth 37 we read that Betsal’el made the ark of acacia wood and then covered it with gold. In verse 6 we read that he made a lid of atonement of clean gold. Questions: Was this mercy seat solid gold? Was the mercy seat and the cherubim made of one piece of gold? How many wings do cherubim have? I have heard that they have four wings, but on sketches or replicas of the ark I have only seen cherubim with two wings? Shalom

Again I must point out that the term "mercy seat" in this context is not from Jewish tradition. The "Kapporet" was made of solid gold and the cherubim were made from the same piece of gold. The commentators seem to indicate that there were only two wings.