Enclosures, devices with a friction stir weld, precursors thereof, and related methods

An enclosure comprising:

• a metal base comprising:
• a horizontal bottom and a base cavity defined by the bottom and vertical base sidewalls at a base perimeter,
• an outer sidewall surface extending along the base perimeter that includes a shoulder, an upper sidewall surface above the shoulder, and a lower sidewall surface below the shoulder, the shoulder comprising a lower portion of the upper sidewall surface connecting to a horizontal shoulder surface at an interior shoulder corner, the horizontal shoulder surface extending horizontally from the interior shoulder corner to an exterior shoulder corner, and an upper portion of the lower sidewall surface extending vertically from the exterior shoulder corner;
• a cover located over the base to enclose the base cavity, the cover including a horizontal top portion extending over the base and a lip at a cover perimeter, the lip extending in a vertical direction relative to the horizontal top portion, the lip including a lower lip portion that contacts the shoulder when the cover is installed over the base;
• and
• an interference fit between the lower lip portion and the lower portion of the upper sidewall surface, wherein the interference fit includes from 1 to 6 mils of interference on each of four sides of the perimeter.