Abstract: A building system including a slide-like construction member which is movable on two guides. The guides are formed by two rods or tubes having a circular cross section. The construction member is formed by two bearing blocks, each of which comprises three ball bearings of the same diameter. The axes of the ball bearings are situated in one plane and are tangent to a circular cylinder having an axis and a constant radius. The shafts of two ball bearings are rigidly connected to the relevant block, while the shaft of the third ball bearing is adjustable with respect to the other two. These two blocks can be interconnected to cooperate with the first one of the rods. The system further comprises a third bearing block which supports two ball bearings of the same diameter, the shafts thereof extending parallel to each other. One ball bearing is rigidly connected to the block, while the other ball bearing is adjustable.