A cigarette package, in some embodiments, can comprise a tray, a cover coupled to the tray, and a cigarette holder secured to the tray and adapted to move between a first position substantially inside the tray and a second position substantially outside the tray. The first reference threshold voltage is set to be different from the second reference threshold voltage. The friction stir welding apparatus also includes a first shoulder not substantially rotatable relative to the spindle housing about the axis and a second shoulder not substantially rotatable relative to the spindle housing about the axis. The most preferred starting monomers are phenylacetylene, 4-ethynyltoluene, and 1-ethynyl-2-fluorobenzene.