This is by no means an advance build, any one can do this easy project. It's not designed to be a permanent Bluetooth headphones set, only temporary. The materials cost depends on where you get them from, but for me the Bluetooth receiver was a little under £7, it came with the small aux cord, and the headphones where ones lying around my house. As long as the headphones have a aux female port then this should be a easy project for you. Otherwise your headphones won't be very applicable to this temporary solution.
Step 1: Step 1: Parts Needed
The parts needed are very basic and simple to use. We need threes things, headphones (with a female aux port), a Bluetooth receiver ( a cheap piece of technology one can buy on Amazon, AliExpress etc for under £10), a short aux cord and some means of sticking the receiver to the headphones (I went with clear tape, but anything will do really).
Step 2: Step 2: Assembling
For this part, we are going to choose where we will stick our receiver, I chose just above the earpiece as it fit quite well. Make sure to leave the button facing outwards so it is easy to access. After you select the place you want to put it, stick it on however you like. I'm going to use regular clear sellotape, but glue would work too.
Step 3: Step 3: Aux Cord, and Powering On.
For aux cord, I would recommend a right angled output, but a normal one will do fine it will just look a bit more off-putting. I wrapped the aux cord around the earpiece once just because it was a bit long. When powering on beware that the receiver might say "POWER ON" and render you deaf for the rest of your life. This warning goes along with pairing and powering off. Now you might say this is a stupid project, but it is a cost cutting method of making Bluetooth headphones without buying expensive ones, and still being able to use your old headphones pieces with all these new technologies etc.