Have a new computer that only has one audio port? Have a separate set of headphones and mic? What to do!?
Make an adapter!
All you need is (all parts except tools salvaged/found from e-dumps)::
2x 3.5mm audio ports
1x 3.5mm speaker/mic male end
Some bits of wire
(Also solder, soldering iron, glue sticks and hot glue gun)
The layout for the combination audio jack is pretty much the same as a
standard stereo jack except the bottom-most sleeve is split into 2, making the top 3 contacts the same order as a standard jack and the bottom-most contact set aside for a mic.
The other side of the jack (the part you solder onto) can be different depending on where you obtained it from, in my case the contacts on the other side were just mirrored of what they were on the other (though I'd recommend using a multimeter or something to check connectivity if you have one that looks different)
Step 1: Solder the Jack
Start soldering the wires onto the jack. It helps if you bend the end of the wire first so it makes a good contact with the small soldering surface of the jack (note: I used a third hand thing for soldering, do not try to hold the wire and solder it at the same time as it will get very hot.)
I used red and white for audio right and left respectively, green for mono mic (only one mic contact so only mono is possible), and black for common ground.
Step 2: Solder the Ports
Solder the other ends of the wires onto the ports.
Some audio ports have different pin-outs, it can be pretty easily figured out by looking inside the port with a flashlight and seeing where each contact leads (remember, sleeve is ground, ring is right, tip is left) or by using a multimeter and a male-male 3.5mm audio cable. It helps if you make a loop or just bend the wires around the pins before soldering so the don't move around.
Make sure you connect the mic wire to both the left and right pins on its port so you get both channels.
Step 3: Insulate
Insulate to prevent accidental wire touching and shocks!
I generally use hot glue to insulate projects since it goes anywhere you want and isn't as shape-limited as shrink tubing.
Step 4: Done!
Enjoy your new, easy to use combo port merge adapter!