the issue is that whenever I try to sweep for exemple a part of the arch or the whole arch itself along the top curve, I will always have some parts that are not intersecting and so on. Do you know if there is any other way around this? I tried already the sweep1 and sweep2 also the loft but nothing seems to work out for now…..
I rebuilt your curves and then created the organic form using a Network Surface, which I trimmed afterward. The issue comes from having two separate lines instead of one continuous curve — Rhino will split the surface at the join. To fix this, you can either Rebuild the curve or redraw it using the Interpolate Curve command.