Ok here is a weird one. I want to achieve this:
Note it is a polysurface. I achieved it by boolean from this something like this:
The boolean functions do not work in rhino 7 for the attached file (was drawn up in 7), but the same geometry exported as a rhino5 file and opened in rhino 5, does work and achieves the result above.
Curve from intersection for some of the extrusions in Rhino 7 gives some wild results too.
Why does it work in rhino 5, but not in rhino 7?
Here are the files:Dropbox - Boolean problemv5.3dm - Simplify your life
Dropbox - Boolean Problemv7.3dm - Simplify your life