We developed a monolateral external fixation system for bone elongation easier to assemble than commercial systems since the clamps can be laterally assembled to the rail in contrast to the commercial systems where the clamps can only be assembled from the ends. The system is formed by clamps, screws, and a rail. The rail is composed of two carbon fiber circular rods of ½” diameter and 42-cm length. The clamps can slide with respect to the rail to allow bone distraction or may be fixed to the rail by using a wedge and a screw. The prototype was mechanically evaluated under the ASTM F1541 standard. The stiffness in axial, Medio Lateral bending (ML), Antero Posterior bending (AP), and flexo-torsional load were 117 N/mm, 46 N/mm, 8.7 N/mm, and 5.8 N-mm/°, respectively, which are on the range of stiffness of commercial systems.