Rashi link
What Rashi says about the Ark of the Covenant:
Verse 10: They shall make an ark---
similar to boxes which are made without legs--- made like a chest called escrin [in Old French] which rests on its bottom.
Verse 11: You shall cover it inside and out.
Bezalel made three arks, two of gold and one of wood. Each one had four walls and a bottom and were open at the top. He placed the wooden one into the [large] golden one and the [small] golden one into the wooden one. He then covered the upper rim with gold. Consequently, it was covered [with gold] on the inside and on the outside.
Golden crown-like rim.
There was a crown-like [ornament] circled around above the edge, for he made the outer ark taller than the inner one so that it rose up against the thickness of the cover and somewhat above it. [Consequently] when the cover was lying on the thickness of the walls [of the inner arks] the [crown-like] rim rose above the entire thickness of the cover a slight amount. This was to symbolize the crown of the Torah.
Rashi on Terumah/Exodus 25: 11link






