At work (I’m a Mechanical Design Engineer) I had to render a model of a video intercom to get a realistic shot. I already had all the parts as CAD models, so I had just to export them in STL format and import each file in Blender. All but the cable.
Even if I’m not a good Blender modeller, I thought that it could be easier (and cleaner) modelling it into Blender than into the CAD software; furthermore I could easier apply modifications to adapt the shape of the cable to the position of intercom body and handset.
I wrote a two-part tutorial where I described how to model the spiral cable.