Abstract: A rectangular building block is provided with an upper and lower surface. The block has a pre-determined thickness, b, width, 2b, and length, 4b. The upper surface of the block has a first central symmetrical channel with length 2b and rectangular cross-section with width 2b and depth b/2, intersecting at a right angle 2 and on top of a second central symmetrical channel on the lower surface with length 4b and rectangular cross section with width b and depth b/2. The building block allows for numerous interactions which enables the creation of a large variety of structures.