u00b0 45 u00b0 90 u00b0 triangles in fig2 the flap 108 is folded down over the face of zone 102 while flap 110 is folded rearwardly behind zone 102 in fig3 it can be seen that in an erected deployed state the flaps 108 110 do not rest against the zone 102 but make angles therewith so as to cover or encompass a three dimensional space 112 indicated by the dotted line in fig4 there are shown two elements 100 and 200 which in this case are mirror images which are laterally joined to one another along fold line 114 and its continuation 116 in fig5 the unit 100 200 is shown in deployed state wherein lines 114 and 116 form an angle therebetween while central zones 102 202 also form an angle therebetween the space encompassed thereby comprises space 112 plus 212 however when elements 100 and 200 are folded together they stack and their profile is identical to fig2 in fig6 there are shown two elements 100 and 500 which are joined longitudinally where zones 108 and 508 are joined so as to be integral and planar in fig7 the unit 100 500 is shown in deployed state where the space encompassed by unit 100 500 is space 112 plus 512 in fig8.