Abstract: A solid geometrical puzzle comprises a plurality of basic components each of which is hinged along two edges to neighboring components. A typical basic component comprises a solid element that is triangular in cross section, said triangle being a right angle isosceles triangle. The solid element has three four-sided faces, a lower face, an upper face extending 90.degree. to the lower face and a face joining the free ends of the upper and lower faces. The end portions of the element are triangles. The assembly may be folded along the hinge lines of a particular type to form many regular and irregular geometric shapes such as sawtooth configurations, parallelpipeds etc. The arrangement is intriguing and interesting to work with as a form of amusement and special effects may be obtained by printing designs on the faces.