An arch 40 is formed in the fold of panels 36 and 38 so as to create a downward biasing force on flaps 36 and 38, which holds {HEAD ~ flaps} 36 and 38 in {TAIL ~ contact} with base 32  
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An arch 40 is formed in the fold of panels 36 and 38 so as to create a downward biasing force on flaps 36 and 38 , which holds { HEAD ~ flaps } 36 and 38 in { TAIL ~ contact } with base 32
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH