I am currently experimenting a lot with CAD design. A few years ago, I tried out FreeCAD, an Open Source 3D CAD solution, and found that it was quite unstable. I anyway managed to make my first 3D design with it that I later even 3D printed. Due to the problems with the software I was not very impressed. However, I recently had to design something for a new project and revisited FreeCAD, and was very happy to see that the instability issues were mostly solved. I only had a single crash while designing a mount plate for a servo, and to be fair, this was after stress-testing the application a bit by clicking more or less each and every button on the interface to see what it was doing.
The project I am working on makes use of Tower Pro SG92R micro servos. For the price they are very powerful, however, I would expect the precision to be less optimal since they are made from plastic. To design a mount-bracket for them, I required a CAD design for the servo, but I could not find a good one in an open format with correct measurements. Therefore, I had to created my own (the original model is colored):
If you want to use the model yourself, you can download it from GrabCAD.
This model was created in FreeCAD. I can recommend the software now, at least for simple designs!