A heavy but durable solution I used once is flexible copper tubing available at most hardware stores. It is used a gas/oil lines in houses. It tends to be bigger than you need, but it does work.

> My Cape Charles has the Feathercraft rudder kit on it, with the black
> plastic housings for the rudder cables to run through. I'm not real
> impressed with the durability, the cables will eventually cut through the
> plastic, and it wont be fun to replace. HVAC systems use pneumatic tubing
> with a little thicker wall but it is still plastic. Any better ideas?
> Perhaps bicycle cable?