About the automatic sweep :)
I have an headache for modify verticaly just the extremities of a curve straight line with only 2 profils
before to see that I must enable the Twist "Flat" against "Freeform" !!!
I had obtain a mysterious twist as soon as move the second extremity! :)

And also that the click on the left path or the right path gives not the same result!
The inverse!

Flat Direction is also a funny option! :)

Now all seems clear for this crazzy function :)
I will made a little video about all that :)

Hi Pilou,

> And also that the click on the left path or the right
> path gives not the same result!
> The inverse!

Yup, that is how you control how the sweep will be done in auto-place mode.

Say for example you want to sweep these profiles along the other path curve:



There are 2 possible ways to create the sweep - which one is used can be controlled by which end you clicked nearest to when selecting the path curve.

For example if you select the path curve by clicking on it near this end, you will get this result:



But if you select the path curve by clicking on it near the other end, you will get this result instead:




So with auto-place mode there is an ordered list of profiles in left-to-right order, and the first one (the one that is all the way to the left) will be placed on to the end of the path closest to where you clicked on the rail path when selecting it.

- Michael