I haven't used the Planar Sections option -- but I thank you for suggesting it! There are still some complex geometries that take a lot of time to get right. The Planar Sections option might help in such cases. The main technique that I wanted to offer is that where I can draw rough curves on a surface in order to 'see' what I want to do next. Then, use Project -- from an appropriate plane -- to get a fair curve that is actually on the surface. That curve is adjusted and used to trim the surface. All this must be done Before using 'Blend', as you have to have corresponding edges to work with. I also want people to understand that the limitations of 'Blend' and 'Network' can be largely overcome by using both of them together. There are several other tricks that I use but did not mention. 'Network' has a tendency to curl the surface as it approaches an edge. To fix that, I usually use 'Iso' to give me some curves that lie on the not-quite-right surface. I often 'Rebuild' these curves, reducing the number of points, which washes out a lot of minor distortions. Then, I adjust the points on these curves, near the curled edge, so that they are tangent to the surface. The trouble with 'Network' is that it doesn't take into account the form of adjacent surfaces, so we have to provide enough information so that those intersections will be tangent; and this is what I'm talking about. When I have those new curves corrected, I run 'Network' again and the curl at the edge is gone. I didn't mention a problem with 'Blend'. You have to break up a 'fillet' at every intersection, as you cannot add edges (as you can with 'Network'). And when the geometry is complicated, those short sections of Blended 'fillets' don't fit together well. They may look okay from a distance, but it you zoom in, you will find that there is a gap or the edges overlap. But if you use those Blends only to give you cross-sections (which are properly tangent to the adjacent surfaces), then delete those Blends and run 'Network', everything fits without errors.