Hi bartosh,

re:
> 3 or 4 edges - select edges and click network button
> more than 4 edges (flat) - select edges, click planar button, fire script: "ShrinkTrimmedSrf" (why there is no button for that?)
> more than 4 edges (curved edges - flat face) - select longest curved edge and extrude it, trim rest and cut out

It's usually best to focus more on the shape of the surface than the number of edges. If it's all on a single plane it's better to use Construct > Planar on that for all numbers of edges, including for 1,2,3, or 4 edges. That makes a simple plane for the underlying surface which can then get special case handling for intersection calculations.

Network is more of a last resort method, if nothing like Planar, Extrude, Revolve are a match. If you use Network on flat curves it will make a surface there but it won't be a simple 4 corner point plane and so it won't be able to get special case intersections with it.

re: ShrinkTrimmedSrf, there isn't any button set up for that because it's not generally very useful, if you have a flat area just use Construct > Planar and don't use ShrinkTrimmedSrf afterwards unless you have some special situation like you want to modify the surface control points. It's normal for an underlying surface to extend out a ways, it's not something you would normally need to try and avoid.

- Michael