Three bars kit to build polyhedric structures based on the law of Cosines

The three bars kit is constituted by three kinds of bars, where the bar of kind (1), has uniform square convex hull section along its length, and both the other two bars, the bars of kind (2) and (3), have equal and uniform regular hexagonal convex hull sections along their lengths, such that the height H of the hexagonal convex hull section is related to the length L of the side of the square convex hull section by the following formula: H=(sqrt(3)-1)xL. This kit allows the construction of three-dimensional structures with one or more of the following characteristics: - Structures made of polygons such that each triplet of mutually adjacent polygons creates one of four "triple connections"; - Structures containing one or more groups of bars mutually connected in parallel;- Structures containing polygons whose edges have integer length; - Structures made of planar polygons such that each pair of polygons connected by a common edge creates a dihedral angle of 0, 60, 90, 120 or 180 degrees; - Structures containing bars of different scales; - Structures containing one or more groups of four bars mutually connected with four standard connectors, two of the bars being of the same kind and the other two bars being of the same kind and parallel. These groups of four bars constitute "quadruple connections"; - Structures containing one or more groups of two or more non-parallel bars connected with a single standard connector.