Is it possible in any 3D printing software to create a coiled tube?
I managed to do it in the end using AutoDesk 123D.



Did it by making two coils of differing radius, then subtracting the smaller from the larger. I made each coil using the instructions found here:


                
            

So there we go...

Printed it out just now without supports - in the orientation shown - and it came out fine. Used a brim, though (don't want it rolling away!)