As others have suggested, use compressionless cable housing.

However i am using brake cable housing for my fd and it shifts flawlessly. The only reason i use it is that it is stronger than derailleur cable housing and there is no way the coil would poke out of the rubber outer. My previous set up using derailleur cable housing failed because the strands poked out of the rubber outer.

Full length is simpler to cut, install and remove. Just one cut and two ends to finish (if needed).