Mr. Albini tried to get Beyerdynamic to make the M380 again, again and .. again. Beyerdynamic answered that they don't have the parts and machinery to make them again... so if the current capsules were up to the task, Beyer could easily have reissued the M380. You can find more info about this in an interview Beyer did with Steve Albini a few years ago.
As headphone drivers the new capsules are not too far from what came out of the old capsules* - reversing them as microphone capsules is something else alltogether. You can try this with any headphones you have - try to use them like a mic and put them in front of a sound source or maybe put them in front of a monitor speaker, record some music. Then compare that by listening to the source track on these headphones. Then listen again on your monitor speakers to what your headphones recorded.
If you do a picture search you can find more info on the old capsules.
When i was at the Beyer factory last year, i spoke to the man responsible for the production of the current capsules and he took the time to show me all the machinery in action. It is remarkable how much effort is put into making all this stuff and how much handwork is still in use - as they said everything a machine can do just as good, they let the machines do. But some steps can't be done by a machine THAT precisely and so the women there do them by hand and with the help of veeery big magnifying glasses, microscopes and so on.
I also saw how they build the other classic mics (M88, M201, etc.) by hand.
I told them i had come across a box of unused capsules and asked them if i should make a few mics for Mr. Albini. As Beyer had wanted to make him happy for some years but were unable to do so, they gave me permission ... and as Mr. Albini knew me from the Electrical Audio forum (i had given them capsules as spare parts for their M380s some years ago) he got his first mic last november, and a second one later. Steve happy, Beyer happy, me happy.
Give yourself some time and set up an automatic ebay search - you surely will snipe some of the right headphones. And to the question how the figure-8 pattern results: the membrane is suspended in a kind of "open baffle" in a round "cradle", with sound being able to emanate from the front and back. It is not two drivers coupled. The reason for this is the need for preventing sound from the back of the capsule being reflected back to the front, that would resulti in phase errors and comb filtering.
*when they did the new machinery to produce capsules, all they had in mind was meeting the specs as headphone drivers, with some new materials and methods of production.
