There already is a wooden T50RP mod called Thunderpants (not made by MrSpeakers), but they seem to have a very colored sound signature that does not fit well with the signature of the Mad Dogs. I like the neutral approach (as in Mad Dog) more since it fits very well if you listen to a wide arrange of music genres. And I don't think that a wooden cup would make the Mad Dog any more neutral than it is.
The Thunderpants is also poorer quality and the manufacturer Gary is flaky.
Best not to give him your money.