Hi Brian,

Thank you very much the detailed explanation and script.
I downloaded it and have made some headway. Please bear in mind I'm not
a 'technical' guy so I'm struggling a bit with a few bits.

I think I managed to unwarp the inner and outer parts:




I'm afraid I don't follow this:

"If a normal to the outer face is drawn at the top, the top of the inner cone extends past the outer cone by "extendDistance", equal to the distance from where the normal intersects the inner cone, to the top of the inner cone.
At the bottom of the frustum, the outer core extends past the inner cone by the same amount, "extendDistance".
So align the "outer_planar" face with the "inner_planar" face, offset by "extendDistance", at the non-slantseam edges, at both the top and bottom edges.
Also, separate the two planar faces by the "frustum_thickness".
Connect pairs of the 8 outer corners with lines, and apply Planar. Join to solid thick planar object."

Would you mind clarifying please?

Apologies for not getting it :)
Gunter