Attached Link: http://www.sams3d.com

It doesn't matter what one you choose, those are all good, we use AutoCad to model ours, but I do know lots have 3DSMax and Rhino, some have Lightwave and Truespace....depends on your budget, one thing you will have to study, ask questions and be patient, but once you get it, you will have a ball, even when you learn you will have fun....I am partial to AutoCad, but that is quiet expensive and very engineering oriented, if I had to choose I guess my pick would be Lightwave..... Sharen