If you've ever tried to learn a CAD program you would know it is not for a weak stomach. The learning curves can drive you nuts and with the countless updates the interface changes and it's all over again.
SketchUp on the other hand has a very unique and intuitive tool set and an easy to follow video tutorial database that will have your project designs up and running in a matter of minutes....literally!
SketchUp is FREE and comes in many languages... Download It Here
The Tutorial section that I spoke of can be found here... Video Tutorials
As well as the Self-Paces Tutorial section ... Self-paced Tutorials
The jewel of Google's SketchUp, it's dedicated 3D Model Database where you can share your work, view and download other peoples work, as well as combine your effort with others and work on a project together.
SketchUp Community is always coming up with some new additions. Check out some of these additions(plugins) here... Plugins ... There is a word out on the net that SketchUp will soon have CNC support