Hi Xavier
Welcome to the forum.
I am interested to know which MD you have built, because I too have built my own surf pi 1.2 and I am in the process of building a waterproof surf pi pro with dual field coil. I have just completed the coil housing and the coils,which must still be tested before sealing it all up. I have also made a straight shaft for it. next I will have to attempt to build waterproof head phones