After comparing the dome membrane of the HHKB Lite and the IBM M3, I wounder if I could just take the domes from the M3 and cut them down to fit the Lite? If that is not possible, I wonder if it would be possible to make a mold and make custom dome membranes.
As I said in another thread you can design about any feel profile into a rubber dome. Except, I did not mention this, I see no way you can make them feel crisp. They are always going to feel a bit mushy which is why I do not think you can make a superb keyboard with them. As for that crisp feel I can think of no way to get it except with a mechanical action.