Print parts (tube_part, bottom_part, cable_stopper)

download the model data  from project's website,
and print the parts (tube_part, bottom_part, cable_stopper(s)).
  
model data is same as regular NSC Microphone.  
PLA, Standard Quality or higher is recommended.  

Get headset

get a headset for smartphone,
and open the package.

in this document, it is instructed with "Hands-free Mic-headset Smart Phone" by DAISO, that has  a condenser microphone of 6mm diameter, costs 100 yen.
the model data is designed for a condenser microphone of 6mm diameter.

Take off microphone capsule

split off the cover of microphone,
and take off the condenser microphone capsule.

Separate microphone cable from earphone cable

separate the microphone cable from the earphone cable.

Put microphone capsule through bottom part

Put the microphone capsule through the bottom part.

Put earchip on microphone capsule

Take off the earchip (rubber part to fit the ear) from earphone,
and put the earchip on the microphone.

Set cable stopper

choose a cable stopper to fit the cable,
then put the cable in the cable stopper,
and set it into the bottom part.

Connect bottom part and tube part.

Connect the bottom part and the tube part.

Finish!

TRY RECORDING!
you can use it as a regular external microphone with smart phone.    
sensitivity is relatively high, so take care when you record loud sound.  
  
and let us know your use case and arrangement!