Google SketchUp is a free offering from Google to rival paid 3D modelling programs like AutoCAD.
Google SketchUp  is a mixture of powerful drawing tools and an easy-to-use interface that makes it a unique 3D modelling tool. With this SketchUp utility you can design almost anything, right from houses to space ships, only barred by your imagination. The designs can be perfected by adding textures, glasses and be tuned to be dimensionally accurate. The true-to-life textures of glass, concrete and other objects simulate real-world objects in your models. Anyone can start with the basic shapes that the program offers and go on to change it to any model they wish to emulate.
Google SketchUp gives you the choice of either printing your models, or use it in Google Earth. With all its functionalities, this program is a must have for hobbyists to professionals.
Google SketchUp is designed for Windows 2000, windows XP and windows Vista Operating Systems.