How to smoothly cap this object ?

 From:  Frenchy Pilou (PILOU) 21 Apr 2016  (11 of 36) 
7928.11 
:)
Render with the new SimLab Composer 7 Public beta http://www.simlabforum.com/viewtopic.php?f=12&t=9902#p15271

http://moiscript.weebly.com/uploads/3/9/3/8/3938813/chair_to_capb.3dm

EDITED: 21 Apr 2016 by PILOU