Here is another idea, the winding wire round another is a great idea, it does give a spiral result and I think the conduit in the picture is in the form of hoops round the tube, so I took a rod (carbon as this was handy for this example) and slid some of those tiny rubber 'o' rings you can get from Model Fixings onto it, spaced them roughly, slid over a piece of heatshrink and wham.....

This one is around 5mm diameter, but if you used a thin piece of plastic rod, and smaller 'o' rings, which I know you can get you could make very cheap and flexible conduit like in the picture.

marcs