In Rhino 8 there is a fantastic tool named push/pull. This can even extrude a part of a surface by put a curve on a surface. What should be more great is if this also works on a edge. So, workflow could be, same surface, same curve on surface. But now it pulls the part of the edge like it do on the surface with push/pull.
Correct me if this already excist and I haven’t found it yet.
First by select the edge througth ‘sub-object’ (ctrl-shift-clic) and move it as you want. It works with vertex too.
Second way, with ‘ReplaceEdge’ command, by split the edge and use a polyline as reference for the new position. A limitation is that the surface needs to be extended to cover the polyline.
I’m not sur if it’s what you aim for but I guess we are close.
Thank you for taking the time. This works, but the same with the old method of extruding a surface and the new push/pull command this works better if I just can make a line on the surface and pull that edge part. This is more a suggestion for Rhino 9…
This is what I mean. The first is a surface with a curve on a certain place. If I want to extrude the surface, now with push/pull it’s easy (read, less commands) The third is with a second red surface. Now this red surface should be extended like the way push/pull working now. If there is a line, you can extend that part of the surface. If there is not in this version of Rhino, my suggestion is to add it in the next version.
Push pull should work also on flat surfaces; at the moment every solution I tried give a separate surface that you have to manually merge to the master one.
Splitting the edge, subselecting and extruding with gumball gives a separate surface too (if the surface is planar and the edge extrusion is coplanar, would be easy to merge toghether)