Abstract: A set of elements have square surfaces with patterns thereon, the elements being arrangeable such that the square surfaces are juxtaposed to form a design. The patterns are defined by one or two contour lines on the square surface, the surface areas on either side of each contour being different colors. The square surfaces have patterns belonging to two groups or have no pattern thereon. The first group includes square surfaces having only circular arcs as contour lines and the second group includes square surfaces having only straight lines as contour lines. The first group includes four types and the second group includes two types.

Abstract: A constructional toy set has building members and coupling members having dimensions which are equal to, multiples of, or specific fractions of a basic unit size, have a basic thickness or a multiple thereof, have through holes of basic hold diameter or multiples thereof with shapes symmetrical to either or both longitudinal and transversal axes thereof. End regions of the members may be semi-circular in form, and the through holes are positioned on the longitudinal axis or symmetrically to the sides thereof and at distances from themselves and the outermost points of the end region equal to set fractions of the basic size, equal to the basic size or to multiples thereof. The coupling members may be joined by threaded bolts and whose length is several times as long as the basic thickness. Nuts engage the bolts to lock the coupling members together.