Update:
Shift_Six has come up with a killer corona gorda mold, and he is going to post the download link to those files here.
Meanwhile I got a quote on the bottom half of the mold from shapeways.com: $287 using their cheapest hard plastic.
So, we have to look for options, e.g. friends with machines, etc. and post any helpful info we find. I'll be looking for alternate possibilities and will post anything I come up with. But I think we gotta make this a community effort at this time. Good luck and thanks a huge ton to Shift_Six for his talent, energy, time, and willingness to help.