I was able to fabricate an insert for the 3063 drum for 7x17. See this link:
(there was a url link here which no longer exists)
It's a bit crude, and you have to watch (in the dark!) what you are doing when you load it, but it develops film fine.
I realize this is a very old thread, but what developer were you using? which side of the shelf liner did you have toward the film - the smooth or the ribbed? How have the button fixtures fared in the intervening two years?