RE: Why is it so hard to make servo extensions?
For a small job like a servo wire, it is not practical to get the wire hot first. Just flux the wire, add solder to the tip of the iron, and touch the wire to the tip of the iron. Now the wire is "Tinned".
Place two tinned wires side-by-side, and again, touch them to the tip of the iron.
The solder that is already on them is usually enough to join them. Additional solder is rarely needed.