This invention describes a set of building elements comprising a uniting plate (1) and a base plate (19). The uniting plate (1) comprises two plates (3) defined in a single plane, said two plates (3) are connected in a connection line (9), and a slot (5) is placed at said connection line; said slot (5) may engage with a slot on another uniting plate (1) to obtain uniting plates with their plates (3) in different planes. The base plate (19) being substantially planar having three parallel plates, which is placed in two planes, where the first (117) and third plate (119) is placed in one plane, are arranged on either side of the second plate (121), which is placed in the second plane, and where the two parallel planes define a space between the two planes to obtain one of the plates (3) of the uniting plate (1). The base plate (19) comprises locking means for interacting with one of the plates (3) of the uniting plate (1); said locking means comprises at least two parts, where the at least two parts are at the first and third plate, respectively and where one of the plates (3) of the uniting plate (1) can be placed between the two planes. The set of building elements may be used in areas like toys, furniture and decorative arts to obtain three-dimensional structures.