<p>The three-dimensional prism puzzle includes an internal mechanism including a cylindrical body divided along a vertical axial plane into two identical portions mutually adjustable by rotation about a radially extending connecting pivot fitted centers. The prism has external exterior segments nominally grouped into three horizontally layered assemblies or structures, namely a middle structure and two adjacent peripheral structures. The cylindrical body portions have at their ends radial projections for mounting exterior segments belonging to the peripheral structures, which segments are provided with complementary recesses, and the shape of these exterior segments is defined by four vertical planes traversing the geometrical center of the prism at an angle of 75 DEG with respect to intersecting vertical faces of the prism. The exterior segments of the middle structure are fastened on respective portions of the cylindrical body of the internal mechanism the dividing plane of which includes with a longer opposite face of the exterior segment of the middle structure an angle of 15 DEG . The ratio of the length of the base of the prism to its height equals cos 15 DEG .</p>
