Bob, I turned the form to the desired shape per normal. I hollowed the piece using a rig till the walls were just over a 1/16". The rest was done off the lathe. I laid out the carving and piercing, then did the piercing next. I then went back and carved the ribs. Had to be real careful. The webbing between the ribs is REAL thin. I didn't try to measure it. Then lots of sanding (mostly by hand). It is surprisingly strong despite the thinness and piercing.