After some search  by google i can say this kind of program's is interesting, well i download the rcCad v2.2.1 and in true is very useful program but
have, A little problem need the serial number (product key )  is not free, and also can using in education, but i believe may Ejs can't done this kind of projects,
however im gonna search  more in my free time may later can design projects like what they done at them website!