Thanks Kevin, I tried different types of cables and small hoses but the thing that worked the best for me was 0.8mm shrink tube.
I could have this easy and kind of cheap (1 dollar, 1 meter) and its exactly the color that I wanted to have, other thing I liked about this is the text on the hoses. Its difficult to see on the pictures but its there, just a tiny detail like on real hydraulic hoses.
I put the blank metal wire (see pic below) that I used for the injector lines in the shrink tube and shrunk it down for 0.3mm with a lighter and took the wire out.