metal blank 16 illustrated in fig2 in the exact same manner as second series rigid connector 15 explained above except that no bend is made along bend line 73 third series rigid connector 15 34 illustrated in fig1 is constructed from sheet metal blank 16 illustrated in fig2 in the exact same manner as second series rigid connector 15 except that variable bends may be made in either bend line 78 or 79 depending on the slope required as in the sloping roof for the greenhouse 69 illustrated in fig3 first modified second series rigid connector 15 34 39 illustrated in fig2 30 is constructed from sheet metal blank 80 illustrated in fig3 as follows xy support side member 17 34 39 is bent up 90 u00b0 along bend line 73 34 39 y seat member 21 34 39 is bent up 90 u00b0 along bend line 74 34 39 y side member 22 34 39 is bent up 90 u00b0 along bend line 75 34 39 z seat member 23 34 39 is bent up 90 u00b0 along bend line 76 34 39 and z side member 24 34 39 is bent up 90 u00b0 along bend line 77 34 39 y side extension 37 is.