The brass mounts on the corners of this chest are set into the timber, not laid on top of it, and that single difference is what makes them look part of the piece.
A cast mount is a rigid object. The corner of a bombe chest is a surface curving in two directions at once. Bring the two together as they are and the mount touches at a couple of points and stands away everywhere else, leaving a shadow gap along its edges that no amount of polishing hides - and dust settles in that gap for the rest of the chest's life.
So each mount is bedded. It is laid in position and its outline scribed onto the timber, then the wood inside that line is cut away by a shade - following the mount's own back profile, not a flat recess - until the mount drops into the surface and sits down along its whole edge.
Every mount is fitted to its own place. They are not interchangeable afterwards, so each is marked, and they go back to the same corner after finishing.
The result is a brass edge that meets the polished timber with no line of shadow between them.