In the past I tried a quality crimper but found the it time consuming and actually more costly due to the oops factor.

For some years now I always keep large rolls of both the lighter gauge and the heavier servo wire in the shop. For simple extension like an aileron servo I just cut the lead in half and splice in and exact length required. Six solder joints and shrink wrapped of course.

This is far preferrable to stacking a bucnch of various extensions with extra plug that can corrode and in almost every case an excessive amount of wire the current will have to transit.

If its a long run I will use heavier gauge wire that what is used on the stock lead and solder direct.

i counted one time on my Wing P-38's a total of 67 solder joints each but they are a far better installation than could have been acheved with varios stock extensions.

All sorts of weird stuff is possible like one I have a four way 'Y' for throttles and another airplane a four foot Y to the receiver supply so the battery can be shifted from the tail to the nose when it is flown without the engines.

Currently working on a six engine project and I am in the middle of wireing now soldering custom leads is the only practical method.

John