The chosen cutting pattern is mapped onto the previously generated interior surface (a). These cut lines are extruded outwards perpendicular to the inner surface and intersected with the outer surface to generate the cutlines of the outer surface (b).
Because of the complex curvature of the inner surface (= the result from the form-finding process), this method does not necessarily create clean cut lines on the entire outer surface. In the convex parts of the vaults, this method renders clean voussoirs (= masonry units/blocks), but it becomes messy in the transitions to concave parts. The intersections therefore need to be cleaned up and interpreted in these areas to get satisfactory cut lines. Connecting the interior and exterior cut lines gives the vousoirs (c).