Hi Peter,
Finally got around to trying this out. It works…mostly. There is still one twist near the apex (see attached image). I haven’t delved into the code to figure out why. A promising result, though.
BTW – two corrections to your code: there are two ‘next i’ nestings, and the ‘n’ in the first TUBE command doesn’t work (I replaced with NSP/4).
Attachments:
www.brucepwalker.com
https://www.mindmeister.com/65450406
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