-- Slide end-A of the tray, right-side-up, into end-A of the cover. (0 0 0)
-- Slide end-A of the tray, right-side-up, into end-B of the cover. (0 0 1)
-- Slide end-A of the tray, upside-down, into end-A of the cover. (0 1 0)
-- Slide end-A of the tray, upside-down, into end-B of the cover. (0 1 1)
-- Slide end-B of the tray, right-side-up, into end-A of the cover. (1 0 0)
-- Slide end-B of the tray, right-side-up, into end-B of the cover. (1 0 1)
-- Slide end-B of the tray, upside-down, into end-A of the cover. (1 1 0)
-- Slide end-B of the tray, upside-down, into end-B of the cover. (1 1 1)