Hi Michael,

The file is at work so I can't give it to you now, sorry.
About the cut, the issue is not about the projected result from one view. The issue is when I project the drawn curve from the side view if I look through the front view the resulting cut is not matching in this view.
And if I draw the curve in the front view this will be the side view which won't match.
But I think it is completly normal as I'm projecting on a surface. That is my method that doesn't work but I don't have a clue on how to approch this.
I'm trying to make a sci fi helmet, nothing original here ;), but I don't know how to tackle this object.
It's not about tracing already accurate line work, it's about translating a 2D concept to 3D.
I made a sketch in Zbrush and then made a turntable from it, I then used the resulting image as template in MOI to try to reproduce a clean geometry.

Still a lot to learn to be proficient ;)