I have a very complex part and I can't create a specific shell. I s there a way to offset the edges in order to define the limits of my shell...and just using cut extrusion to create a shell???? I hope I am scrutable
Essentially what the Shell command does if apply a normal offset to all surfaces. If the shell thickness (offset distance) is greater than the radius of curvature of a given surface, the shell command cannot construct geometry.
I think what you want to do is:
1. Create offset surfaces using either the Auto Fit or Controlled Fit options. (Insert > Surface > Offset in 2001, Edit > Offset in WF)
2. Merge the surfaces together to form a quilt. (Insert > Surface Operation > Merge in 2001, Edit > Merge in WF)
3. Create a cut using the quilt (Insert > Cut > Use Quilt in 2001, Edit > Solidify with the Remove Material option in WF).
And both 2001 and WF allow different offsets for different surfaces in the Shell command.