ORIGINAL: Sturtz
ITip on fishing servo wires I stumbled onto......... (Elec fence wire) it's soft and bends easy yet it will follow the formers and spar and can be fished out without breaking stuff.
A bit off topic, but I usually use piece of the very thin music wire for this. It is stiffer so it doesn't stay in a bent position after encountering a rib, but will flex to let you you know you have hit it without punching through.