Split cable gland - parameterizable

A cable gland and nut which both split into two pieces, for putting on existing cables where you can't get them over the end. Parameterisable for different sizes of hole and cable.

Not 100% successful: the nut requires quite a tight tolerance to spin on the thread correctly, and the filament I had was too damp to do an accurate enough job. Leaving it here in case it's useful for someone - eventually I reverted to the original and managed to get the nut over the end of the cable.

Requires a long compile time in OpenSCAD - it can appear to freeze but it will eventually finish.