I was just looking at updates to a 3D program I use called Cinema 4D and wouldn't you know it, it now comes with a sculpt section. AWESOME!
New in R14: Sculpting - YouTube
I'm not entirely sure how much use this would be for real world prop building, maybe only good for creating pep files but most of the detail would get lost in the unfolding I think.
Anyway thought you guys might like to check it out.