R/C Hot Air Balloon envelope software

Hi I am looking for software to design the envelope for a R/C Hot Air Balloon.

I understand Bob Nungester's had some software available but the link is dead .(http://www.jps.net/chuck1/empty_pockets.htm) and I have looked all over Googles search engine, can any one tell me if the software is downloadable from some where? Or is there other software that I can use for this project.

Thanks Francis Murphy