Ac3d is a graphic program which looks like autocad. Start the program with the command ac3d. Under
/usr/doc/packages/ac3d/
you will find some demos in the directory acfiles/ and the documentation in html format in the directory manual/ . To read the documentation, start your WWW browser with the argument
file://usr/doc/packages/ac3d/manual/
Please note the message in the dialog window at startup: this program is SHAREWARE and must be registered if you wish to use it.