Yes thx
I have asked that because there is a very practical thing in SKetchup :)
Perpendicular face tools
http://forums.sketchucation.com/viewtopic.php?t=17396

Hi Pilou - one of the nice things about these tools in MoI is that they're multi-purpose - they can orient your circle perpendicular to the end of a curve, or on to another surface with the same tool, it just depends where you put the target point.

Here's an example:



- Michael

Denitively tricky! ;)
That rocks!
I will save some times manipulations with helpers lines and axis rotations object :)
That's funny that we can arrive at the same result with some different method!

Some facts for my futur videos :)