Translating the calculated dimensions for my LED helix into Onshape CAD was a relatively straightforward affair. This 5 meter long LED strip comes with an adhesive backing, so a thin-walled cylinder should be sufficient to wrap the strip around outside of cylinder. This cylinder will have a shallow helical channel as a guide to keep the LED strip on track.

That's all fairly simple, but the top and bottom ends of this cylinder were question marks. I wasn't sure how I wanted to handle the two ends of my LED strip, since wire routing would depend on the rest of the project. A large hollow cylinder is generic but the ends are task specific. I didn't want to lock into any particular arrangement just yet.

Another concern is that an >18cm cylinder would be pushing the vertical limits of my 3D printer. Mechanically it should be fine, but it's getting into the range where some wires would rub against structural members and filament would have to take sharp bends to enter the print head.

To address both of those concerns, I limited the central cylinder to 16cm in height. This would be sufficient to support all but the topmost and bottom most windings in my helix.  This cylinder will have mounting brackets at either end, allowing top and bottom parts of the strip to be handled by separate bolt-on end pieces. They should be much simpler (and faster to print) allowing me to swap them around testing ideas while reusing the center section.

Since this would be a very large print, I first printed a partial barrel in PLA to ensure the diameter and pitch looks correct with the LED strip actually winding around the plastic. PLA is probably not the best idea for this project, though, as bright LEDs can get rather warm and PLA softens under heat. My actual main helical barrel will be printed in PETG.

It was a long print (approximately 26 hours) and a long time to wait to see if it looks any good with my LED strip wound around it. (Spoiler: it looks great.)