1. A computer implemented method for designing a part, wherein the method comprises the steps of: providing a surface and a base curve lying on the surface; sampling the base curve into a list of base points; determining a grid of points of perpendicular geodesic curves, the points belonging to a respective level, each level corresponding to a respective geodesic distance to the base curve, wherein each perpendicular geodesic curve lies on the surface and departs perpendicularly from the base curve at a respective base point; then, computing a plurality of parallel geodesic curves lying on the surface by using the grid of points, each parallel geodesic curve corresponding to a respective level; and displaying a representation of the part.