Tired of sharing your earphones, and have to listen to half the music. But you don't want to spend money on it either.
then this is a solution to it.

ps: I excuse myself for any spelling mistake that might occurred, English is not my native language. But please correct me if I typed something wrong, we're all here to learn.

Step 1: 1# What You'll Need

-jack plug (from the cable of old/broken/bad earphones)
-jack socket (from old electrical appliances)
-wires
-(hot)-glue
-an attractive case to put everything in
-some drill bits and a drill
-pliers
-electrical tape
-a soldering iron is handy but not necessary

the first step is to extract everything you'll need from the old appliances
since this is done by your own method and preferences (from destructive to poetic) I'm not going to show how to do that.

Step 2: 2# the Casing

-pop open the casing and make as many room as possible.
I chose a little toy car for this purpose, and I removed the wheel driving mechanism.

-figure out how you can get as many sockets in as possible and drill the holes make sure that the sockets barely fit, we want everything to be strong and secure.
I have 2 sockets in the roof of the car, and one in a wheel.

Step 3: 3# the Plug & Sockets

-cut off the earphones of the old/broken earphones, so you're left with just the plug cable.
-strip off the protective plastic to expose the wires. they should have a factory color code
be sure to remember which of the wires should activate which ear (left right)

-connect every pin of the socket to a piece of wire and figure out which pin belongs to which wire from the plug

Step 4: 4# Bringing Everything Together

-put every socket inside, and glue it with (hot)-glue so everything is strong and secure
-braid the associating wires and isolate the exposed metal with isolating electrical tape
-close everything up, and glue it shut.

now all you need is friends who want to listen to your music
....
or turn metal, and no one will bother listening to your music \nn/

good luck

NOTE: the sound level dropped once I plugged in the other earphones, this might be a failure in my design or because 2 earphones parallel consume more energy than I originally thought. any way it's solved by cracking up the volume.
just don't plug out one of the earphones when the volume is up! disconnecting one earphone will skyrocket the volume, and blast off your ears!