Of course before soldering anything you need to get the tools and suppies:
[*] Total expenses
In addition, you will need the following stuff, could be bought locally:
1) Stainless steel high quality scissors
2) Ruler - to measure the length of wire
3) Permanent marker - to mark the cut points
4) A4 paper sheets - to use as disposable surface
5) Lighter - better with a hole to refill it later
6) Toilet paper roll - for technical use only ;)
Now, after you got all this, you noticed that 20 cm copper wires are too long for you: decreasing the signal quality or just a little bit inconvenient... This manual below (with nice pictures included!) will help you to learn some basic soldering, giving an example of:
=== How to reduce the length of 1P copper wire from 20 cm to 10 cm ===
So you got this 20 cm copper wire. Look at the picture above, isn't it nice?
Measure about 10 cm / 2 + 0.5 cm = 5.5 cm from both ends of wire and mark these points
Now cut a wire at these points
Although the isolation could be removed by something sharp (scissors or knife) it is inconvenient for 1P wires - too easy to cut some of the wire's hair-thin strands! Here is the alternative way:
1) prepare some toilet paper near you, make sure that you can take and use it very quickly
2) set fire to the wire's end using a lighter and let it burn for one second
3) quickly (!) : blow out the fire, take a toilet paper and through a toilet paper (to avoid burning the fingers) pull the burned insulation from the end of wire before it cools down!
4) if you did 2)-3) not good enough you may need to repeat these steps
5) remove the tiny remains of insulation from the end of wire - using your nails
^^^ you will be able to do that in less than a minute after some practice
Get a shrinking tube of good diameter and length. From a set that I linked in previous article, this is a half of 1mm shrinking tube. Then put it on a wire
Prepare the soldering equipment. Place some A4 paper sheets below it to use as disposable surface (later you will roll them and throw away with some tiny remains of soldering supplies)
Apply some flux at the copper end of wire, for easier soldering
While a soldering iron is on a stand, you could hold both copper wire and soldering wire. Choose a temperature of soldering iron and wait a small time until it heats. Then start putting the solder on copper end of wire until it covers a copper part from both sides. Don't move a shrinking tube too close to a soldering iron, or it will shrink before its' time!
After doing it to both of your wires that's how they will look like ^^^ . Now solder these wires together. Make sure that, while a new connection between them is reliable (difficult to destroy by pulling), there are no significant "solder mountains" that could prevent moving a shrinking tube over the new connection
I still got two "solder mountains" (one big, one small) but they are thin and have a good shape - could be easily removed using the stainless steel high quality scissors
It is easy to remove if your scissors are good - soldering wire is made of a soft material. Just make sure not to accidentally cut a wire, or you will have to start over!
Removed a big "solder mountain"
Removed a small "solder mountain"
Now you could finally put a shrinking tube over the contact...
... and, using a lighter, heat it to shrink
Heat it evenly, don't stay at one place for too long or it will be damaged
That's what you should get in the end. Now it's a time to test this wire. Take a multimeter, turn it on and put into resistance-measurement mode.
Put the ends of multimeter probes inside the 1P plastic ends (if the end of probes are high precision, they are thin enough not to damage) or at those small metal parts looking from a plastic part at wire's ends
If the resistance is infinity or too large, you have either soldered incorrectly or not putting the multimeter's probes in a correct way.
If the resistance is small, congratulations: you crafted a good 10 cm copper 1P wire!