To provide a member to effect assembly at a low cost, simply, easily and accurately by any one, in a member to mount a regular triangular frame material during formation of a regular icosahedron.

In a roof type mounting member which has a development plane shape having a given width and is inclined from a center B toward left and right ends A-C, an upper side ABC angle is 116. 565° at a point B. Mounting holes are formed laterally symmetrically. A segment line to intercouple E, being the center of a lower side DEF, and the center B of an upper side is folded inward and this mounting member is manufactured that 60° is held at the top parts B and E of ABC and DEF.