Rashi on Genesis 2:22/רש"י על בראשית ב׳:כ״ב

1ויבן AND HE FORMED (literally, He built) — as a structure, wide below and narrower above for bearing the child, just as a wheat-store is wide below and narrower above so that its weight should not strain the walls (Berakhot 61a).

2ויבן את הצלע לאשה AND HE MADE THE RIB INTO A WOMAN — לאשה means that is should become a woman, like (Judges 8:21) “and Gideon made it לאפוד ” i. e., that it should become an ephod.