Coupler for threaded flexible hose parametric customisable OpenSCAD

I designed this to use in a 20-pipe crank organ that I'm making, from a popular plan available on-line from its inventor. I acquired some 25mm internal diameter flexible hose which will feed air from the bellows towards the musical pipes. That hose needs an airtight connection with plywood.

This model will be airtight when the thread is filled with PVA adhesive, and is bonded to the plywood with PVA, epoxy adhesive, or silicone-based builders sealant.

My hose has 25mm internal diameter, 31mm outside diameter. The thread has 6mm pitch and 2mm thickness.

On my printer, the .stl file makes a comfortable fit (not sloppy, not tight) suitable for filling with glue. The coupler is 25mm high, walls are 4mm thick (less the thread), and the flange adds 5mm gluing surface all round the bottom.

I found that after changing any of the parameters in OpenSCAD, the preview appeared quickly. But rendering the export file takes a l.o..n...g time on my Windows 10 PC.

The OpenSCAD code uses a library from https://www.printables.com/model/263725-helix-library-for-openscad (Thanks to @GaelLafond for the library)

The OpenSCAD code I've supplied needs the library file helix_extrude.scad to be in the same folder as itself. If you put the library file somewhere else, you'll need to provide the full path to the library file in the “include < >” line.