Funny thing at the opposite of Moi ;)

 From:  Frenchy Pilou (PILOU) 22 Nov 2017  (149 of 3024) 
4446.149 In reply to 4446.148 
Yes it was the tricky use of a simple Boolean Diff between a curve and a volume circonvoluted! :)

EDITED: 22 Nov 2017 by PILOU