Google Sketchup has been recommended to me by a lot of people. Do you have any experience using it? Is it just like any other 3D software or does it have limits (like rough shapes and edges)?
Sketch up is almost perfect for 3d printing applications. I would say It actually has less limits than a lot of 3D packages,but it is a very specific program.The only hang up is the free version has limited ability to export the necessary file types. (example- .obj file extensions are only exported with the paid for version) I would say use the free sketch up version until you learn
3d modeling,then decide what you need.
I don't know why you would use it over Zbrush though? ( Just being that you asked about Zbrush..?) Zbrush,Maya,Max,Mudbox,pretty much being the Cadillac's for these purposes.They are advanced and expensive though. I don't recommend them to anybody who isn't 3D savvy, or willing to learn 3D software all the way. Just focus on the modeling tools of the package if that is what you will be using it for,and again,then see what you need..
hope this helps.
P.S - I posted this as a new thread if you are interested.http://www.pixologic.com/zclassroom/homeroom/tutorial.php?lesson=jeff