Structure for determining shelves and items of furniture

A structure for use in constructing shelves and items of furniture, the structure comprising:

• a plurality of tubular profiles, each tubular profile comprising a body comprising (1) a first external shape that includes four external surfaces forming a first square shape and (2) four internal walls defining an internal cavity having a second square shape, wherein the second square shape is rotated forty-five (45) degrees relative to the first square shape;
• a plurality of nodes, each node having at least two arms, each arm adapted to be fastened inside an end of a respective tubular profile,
• wherein each arm includes a part having a second external shape corresponding to the second square shape of the internal cavity, the second external shape of the part comprising four sides and four beveled corners, the four sides including a first pair of opposite and parallel sides and a second pair of opposite and parallel sides, each beveled corner having a bevel that extends along a length of the part and is parallel to a longitudinal axis of the respective arm, each bevel comprising screw threads,
• wherein the part is adapted to be inserted into a corresponding cavity of a corresponding tubular profile and rotated relative to the corresponding tubular profile, causing the screw threads of the plurality of corners of the part to engage with the corresponding tubular profile, thereby fastening the part, the arm and a corresponding node to the corresponding tubular profile.