Hi Steve, also probably 2-rail sweep is just not going to work for this purpose with segmented polyline rails - 2-rail sweep doesn't know how to produce mitered corners, when there is segmentation it's just going to build the equivalent of small sweeps individual sweeps along each pair of rails, I believe that's one of the problems that you were showing.

If you stick with some other tools like 1-rail sweep, lofting (between same # of segments), extrude, revolve, those would probably work better. Actually Network can work as well with the same number of segments on each side, that may give you what you a similar result that you would be thinking of from 2-rail sweep.

The way that 2-rail sweep works, it kind of drags a frame that slides along each of the rails as it moves along them - this surfacing mechanism just does not particularly have a good way to handle sharp creases in the rails other than in special cases like with rails that have the same shape.

- Michael