What you'll need is an old telephone (the ones with the big metal ringers inside them and the twirly knobs) but all we're gonna use from that is the "headset" the twisty cable and the female plug from the phone with about two inches of it's wires still attached (mine were red, green, yellow, and black)
and to finish it of you'll need two mono male 1/8 audio jacks if you do what I did, but i imagine you could do this another way to.
right now the receiver is a little quite (cause it's not up to line level, but that's for a later time).
Step 1: Soldering
for me red and geen when to the speaker (top)
and yellow and black to the reciver (bottom)
hence i have the receiver as a red and the speaker as black port
I promise my next instructable will be more through, but I've been making things for a very long time and just decided on a whime to do this, I'd apreciate any positive feedback, and let me know how this goes if you to make one of these, or already have.