means for forcing and maintaining the first complementary means in the engaged position this is shown generally at 34 e 34 in fig3 and one side of protrusion 18 in fig3 is designed so as to substantially completely interface with one side of protrusion 18a of the non continuous interlocking assembly element of fig3 explaining the function of the second complementary means in greater detail as the interlocking assembly element lip 12a of the non continuous assembly element 6 of fig3 begins engagement with the groove 14 of the continuous interlocking element 7 of fig3 portion 18a of the second complementary means for forcing and maintaining the first complementary means in the engaged position comes into close proximity with portion 18 of the second complementary means for forcing and maintaining the first complementary means in the engaged position as the engagement of lip 12a in groove 14 becomes substantially complete the two portions 18a and 18 of the second complementary means interface and ultimately snap into place with the complementary side by side engagement of 18a with 18 causing a forced movement of the lip 12a of the non continuous interlock assembly element 6 of fig3 into the groove 14 thus forcing the first complementary means into the engaged position in addition the complementary side by side engagement of elements 18a and 18 as depicted in fig3 serves to maintain the first complementary means in the engaged position so.