Here ya go

Hi Don, yeah if you can post a 3dm file with the curves you were attempting to use that would probably help to better visualize what you're trying to do.

But from your description maybe Rail Revolve would be good:
http://moi3d.com/3.0/docs/moi_command_reference7.htm#railrevolve

- Michael

Modified walls:
Sweep Red obj with green rails.
Leaves a hole in bottom.
- B

Hi Don, so yeah the source of your original problem is that one rail sweep rotates your profile curve to make it perpendicular to the rail tangent as it progresses along the rail.

But if your profile sticks out a further distance than the radius of the bend that will produce overlaps and bunching like this:




So you need instead something that goes like this:



Either two rail sweep like Brian has above or Rail Revolve can produce that type of thing.

- Michael

Thanks all. Rail revolve did the job!