Continuous flat unidirectional flat ribbons, which have been precut from an impregnated fiber reinforced-matrix composite tape so as to have a substantially greater width than thickness, are interlaced in over-and-under relationship in 0 degree and 90 degree directions into the form of a continuous, multi-directional seamless tube. The tube may be cut into tubular sections, which then are subjected to temporary heat and pressure so that the matrix fuses the interlaced ribbons to form an integral tube. The elongated seamless tube also may be cut into planar sections and used to form integral members of planar or contoured construction. The integral members may be formed of a single layer of the interlaced material, or of laminated construction from multiple layers of the interlaced material, with the ribbons of each layer either extending parallel, at an angle other than 0 degrees/90 degrees, aligned, or offset, with respect to the ribbons in the other layer(s). The formed members may have interlaced ribbons of different types and/or contain different types of fibers in different sections of the members, to provide the members with different structural characteristics.