There is another software package I just thought of this morning that might be useful. It is called Moment of Inspiration (MOI) (I am not so hot on the name) but it is good software in any case. The interface is very intuitive and in many ways it is a nice blend of the features found in Rhino and Sketchup. I find it really easy to work with and much more powerful than Sketchup or CB Model Pro. It also reads and writes the proprietary Rhino file format, making it very useful as a supplement to Rhino. The reason I have not bought it is that it is the same price as the educational cost of Rhino ($195). But compared to the full cost of Rhino ($995), it is a great deal. It is a PC-only application, though. In any case, it may be worth a look and a means to get things rolling quickly. There is a demo you can download at the above link.