This one is going to be extremely difficult for anyone to replicate as both pieces required have not bee in production for almost 17 years!
I had been working with this theory for a while. Isodynamic drivers for headphones actually do better in controlled airspace enclosures than in damped, open air systems.
You would need:
Sony MDR-CD750/950/1000 Shell
Basically, you would need to extract and rebuild the driver in the Fostex T20v2 which is very difficult and plastc meld the two sides back together again. Not for a Novice!Fostex T20v2 Headphone
Then, Mount and Secure those drivers to the Baffle for the MDR-CD750/950/1000 shell (MDR-CD750 will require more work on the baffle as its set for smaller drivers). You must also attach Aussie felt to the back of the Fostex Driver.
The shells need to be damped internally with PC damping foam with adhesive backing, plugging of all ports with StickyTac, AND possibly drill out the right shell for direct wiring (original wiring is VERY thin with relatively low conductance).
What you end up with is something that is more comfortable than the original Fostex T20v2 and sounds better than even the standard mods for the Fostex T20v2. The biggest differences are in the soundstage and airiness of the high end as well as more extension in both ends of the spectrum. Please try something like this on your own!