Yay! Christmas balls for everyone!! Thanks @Box, your GIF did not disappoint. I had been using basically the same method for a similar version with joint push pull (but I was not using fixit 101 for clean up which is an awesome tip). I think your advice to ignore the ends and stitch them back together after also saves a lot of headache.
What really happened to give me so much trouble was that I couldn’t help getting tempted to do things the hard way and I had gotten fixated on finding a reliable way of making this shape employing follow-me pathways so that I could test out various spiral columns with different cross sections (circle, polygons, stars). Building a line path that follows smoothly while flipping the cross section 180 and ending square on both ends puzzled me for a bit but I think I have a working version now.
The real game changer here was the tip about printing unsolids. I dove back into my slicer options and have now located the mesh controls to union overlapping volumes and patch mesh holes. Sooooooo much easier it feels like cheating. It’s still darn good modeling practice trying to keep these organic shapes manifold, but it’s great to know I can be lazy if I want to.
I think this one came out particularly nice.
