Just a quick note - if you want to tweak those curves, the sweep should dynamically update.

But the mirrored part won't update automatically - this is because history updating is not turned on by default for the results of mirroring. Some operations (right now including all transforms) don't have updating turned on by default because it can sometimes be confusing for doing basic things when a bunch of other stuff changes.

However, you can turn on updating for the mirroring - to do this, select the mirrored half, and run Edit/History and choose "Enable update" - once you have done that, if you edit one of those curves it will update the sweep, which will then in turn update the mirrored part.

Here is a tutorial that I wrote earlier on making a Japanese bath tub which uses a similar half-edit type thing: http://moi3d.com/forum/index.php?webtag=MOI&msg=402.9


Also, I'm not certain but I think you can still get creases with the sweep that you're doing there, because there will be a type of rotational twist happen in between the profiles as the ends move along the rails at sort of slightly different speeds.

The way you can absolutely guarantee that you will have a perfectly smooth result is to use mirrored+joined profiles, and instead of splitting the profile, keep it intact and mirror that side rail over to the other side and use that as the second rail instead of the central rail. When doing it that way the profiles will not have rotation happen to them since the rails are mirror images of each other and points match up perfectly between them with no "slanting" as the sweep moves along.

- Michael