A mattress foundation includes: a head end panel assembly; a foot end panel assembly; a left side panel assembly; and a right side panel assembly, all slidably attaching to each other using sliding mechanisms. At least one of the sliding mechanisms includes an elongated slot and an elongated protruding element that fits within the elongated slot. A horizontal cross-section of the elongated slot and/or the elongated protruding element includes thin elongated flexible arms, attached at their proximal ends to a common surface, but otherwise extending away from such common surface and separated from each other. When viewed from the horizontal cross-section, the average thickness of the thin elongated flexible arms is substantially less than the length of the thin elongated flexible arms.