I should provide more details on my recommendation for 123D and the FlashForge 3D Printer. I recommend these tools for prototyping. I currently don't need a high quality finish on my prints or precise details on my models. 123D is an affordable tool for simple designs. If you need a lot of complex curvature, that can be difficult. You might also find yourself doing strange work arounds to create the exact shape you want if there's no tool to do it directly. If you want a real pro tool, SolidWords is great, but very expensive.
The 3D Printer will give 0.2mm accuracy on models and is fine for building functional prototypes. It doesn't produce a high quality finish and the printers do require occasional maintenance (re-leveling and kapton tape replacement).