VectorEngineer is a complete technical drawing and multi-purpose cad software system that offers all the features required to create accurate professional drawings, working drawings, designs, plans, layouts and diagrams in a quick and easy mouse driven windows environment. Its great for work, home, education and hobbies and best of all - its available for free, its complete with no limitations, the free cad system has everything you need to produce any kind of drawing, its easy to use and is great practice until you go for the low cost upgrade option of the Pro Tools version.
Pro Tools features a larger feature set and has an isometric 3d design section to make isometric visualisations of your drawings.

VectorEngineer is a 2d cad system originally developed as a technical drawing program to produce working drawings for engineering projects. Isometric visualization was created to help minimise mistakes when using the traditional top, front and side views and to help generate a feeling for the finished object. The screen shot demonstrates this idea and shows the results easily attainable by the system. Isometrics can be built using a variety of shapes, cubes, quadrics, spheres, cylinders, cones as well as plate/wall pieces and simulated holes with true measurements on all sides. All drawing and edit commands are accessed by a floating toolbar which includes extensive viewing, snap positioning, and dimensioning tools or use the extensive menu commands which includes part assembly and saved views as well as all the drawing setup parameters such as unit and grid settings to make for easy and accurate drawing.

The license of this software is Freeware, you can free download and free use this cad software.