Fishing line would work, but it would cut into the plastic and metal.  You would have to use a line that is very abrasion resistant and strong.  That will result in the line cutting through other stuff, unless you put a ceramic eyelet at the in/outlet.  It's best to stick with nylon cord or go with a roto-start type system.  If you look at the new fishing lines they have released, (i.e. Braided lines such as Spiderwire and Fireline)  they are very prone to cutting into older rod guides and reels.  New rods/reels have stronger coated metal or ceramic guides.