To build the Bluetooth headphones these are the materials your gonna need

• CSR8645 bluetooth module
• Micro USB Lithium Ion battery charge control module
• Micro USB breakout board
• Nokia BL-5C battery
• 2 x Dayton Audio CE38MB-32 drivers
• Bose QuietComfort QC15 QC2 replacement cushions
• Plasticine
• 24 AWG hookup wire
• Blank PCB board cut into 30mm x 50mm size
• Solder
• Gel consistency glue suitable for plastic, such as Loctite Gel Super Glue
• 2 x Micro switches
• Slider switch
• Ammonium Persulphate for etching PCB
• Gaffer tape
• Masking tape
• 10k resistor

Now the materials you are gonna need to print are the left and right baffle. left and right cover,volume button, and last the headband. Next you have to mount the drivers, do this insert the baffles into the oriented yellow circles be extremely careful when doing this. Then glue everything and wait until the glue is dry. Now your gonna tune the sound and threes guides online to how to do this exactly Now you wire up the battery side and be careful because some heat comes out of it. Now wire up the audio side then attach the volume button then lastly assemble everything then you are done.

It relates to engineering because your building things.