To use add: use <arc.scad>to your OpenSCAD project, then 2D_arc(w=thickness_of_arc, r=radius_of_arc, deg=degrees_of_arc_angle, fn=resolution); 3D_arc(w=thickness_of_arc, r=radius_of_arc, deg=degrees_of_arc_angle, fn=resolution, h=height_of_arc);you may need to edit the file slightly for small radii and large arc angles (>340 degress)