the best thing about freecad is that its free. in the world where other cad software such as AutoCAD cost a lot this is one of the best alternative solutions. the program is simple and i finding a simple learning curve to the program. also the program doesn't need a lot of memory or CPU to run smoothly.this program doesn't have all the features and quality of other CAD software but for mechanical designing, this is a great tool. the interface of the software is simple enough and not too complicated. it supports multiple operating systems and so many people can take advantage of it. path module is another part i liked about the software. while designing mechanical or electrical circuits i can see its working and easily make adjustments wherever its necessary. there are also many build is models to get you going at first,

OpenSCAD is so amazing because you can create things with code. It's like a little bit of Matlab and a little bit of Solidworks.

The GNU Octave can handle any high end numerical calculation and convert into to graphical interpretation. It is very ideal during experimental analysis of materials. Its biggest advantage is that its an open source programming language.