Hi Bravlin,

re:
> I can't understand what exactly cause the problem with this shape.

Well a few different things - too much variation in shaping between stations, like you have tight bends in the corners and then those collapse down to a pole point for the next station. There shouldn't be so much variation between profiles.

When collapsing down to a pole it's best for the shape to resemble a circle before the pole, something more like the attached file. But overall it's not a feasible shape to try and do with one single surface with poles.

Little skinny pieces are because of sharp corners not being aligned to the other direction's curves:






> The result shape on a picture is a combination of extrude, trim and loft.
> But if you look on it, shape lack of continuity and smoothness on edges.

Can you post the model file so I can get a better look at it?


> But for more square like shapes that also have smooth edges and tilt (so they not easy to
> trim or extrude) i still don't know what to do.

You build an extrusion that is straight and has flat ends initially, then introduce tilt by cutting it with a side profile, something like:









- Michael