after you finish the step 12 or 14, you can extract the curves from solid body.just follow the step as below: % L7 Y% P! G; v+ f1 p0 u2 J+ c- s1: make new layer for new curve. 0 p" X0 o3 E/ }' m2: under modeling, choose Insert--Curve from Bodies---Extract---Edge Curves---All in Face, then select the face of solid bo dy,---ok---0k---Cancel, leave the Extract curve dialoge. 1 Z/ ~! o! C# H3. make the solid layer invisible but the new layer of new curve selectable or work. 8 v" D% `# i; E! \0 {6 ^! D4. that's all.