and hence the print cartridges 30 and 32 in the position illustrated in fig4 when the movable housing portion 16 is in its second position the holding mechanism 40 comprises a stationary arm 42 fixedly mounted to the stationary housing portion 14 a cam 44 fixedly mounted to the movable housing portion 16 a lever 46 also referred to herein as a locking element pivotally coupled to the stationary arm 42 and a spring 48 coupled between an extension 14 b of the stationary housing portion 14 and the lever 46 the cam 44 effects movement of the lever 46 such that it engages the carrier 18 when the movable housing portion 16 is moved from its first position to its second position see fig2 the lever 46 is considered engaged with the carrier 18 when it makes direct contact with the carrier 18 or is positioned a small distance from the carrier 18 when engaged with the carrier 18 the lever 46 acts as a stop to prevent movement of the carrier 18 in a direction represented by arrow 19 in fig4 away from the first side wall 14 a the lever 46 disengages the carrier 18 when the movable housing portion 16 is permitted to move to its first position see fig3 and 5 a packaging element 100 formed for example from expanded polymeric beads is fitted over a first end 12 a of the printer housing 12 to maintain the movable housing portion 16 in its second position see fig1 and 2 the packaging element 100 comprises a recess 102 shaped so as to receive the first end 102 of the housing 12 when the movable housing portion 16 is in its second.