Siempre que doy una charla sobre Software Libre (y si que a muchos otros que dan charlas también les pasa) le preguntan lo mismo y uno se queda casi sin palabras. ¿que programas hay que reemplacen el autocad?

La respuesta es NINGUNO, lamentablemente. Pero, me encontré con una lista de programas que funcionan sobre plataforma GNU/Linux que puede ser útil para mostrar.

De la lista puse los que ví que eran GPL.

-> ADINA http://www.adina.com/ is a program for FEA (Finite Element Analyses) including an object modeler.

-> Alliance http://www-asim.lip6.fr/alliance/ is a complete set of free CAD tools and portable libraries for VLSI design. It includes a VHDL compiler and simulator, logic synthesis tools, and automatic place and route tools. A complete set of portable CMOS libraries is provided.
Licencia: GPL

-> BlenderCAD http://www.blender.org/ is a Blender script created with the aim of expand the functionality of Blender, so that it could be used for CAD. More info on the release of BlenderCAD and the Blender discussion forum. Visit the BlenderCAD project page for download, etc.
Licencia: GPL

-> BRL-CAD http://brlcad.org/ In 1979, the U.S. Army Ballistic Research Laboratory (BRL) expressed a need for tools that could assist with the computer simulation and engineering analysis of combat vehicle systems and environments. BRL software developers began assembling a suite of utilities capable of interactively displaying, editing, and
interrogating geometric models. This suite became known as BRL-CAD.
Licencia: GPL

-> Dr. Geo http://www.ofset.org/drgeo/ is a GTK interactive geometry software. It allows one to create geometric figure plus the interactive manipulation of such figure in respect with their geometric constraints.
Licencia: GPL

-> Fandango http://www.soffernet.com/jaime/fandango/ Scripted 3D CAD engine. Fandango is planned to be a full featured CAD program. It has a C++ core extensible by scripts. It still doesn't do much CAD stuff. Currently the memory core for entity management is ready, scripting works wonderfully thanks to the ease of embedding and extending of
Python, and the keyboard and mouse control are half implemented.
Licencia: GPL

-> gCAD http://gaztelan.bi.ehu.es/~inigo/gcad/ a simple 2D CAD program for the GNOME desktop environment. It is still in its early development stage.
Licencia: GPL

-> GNU-CAD http://gnu-cad.sourceforge.net/ the goal is to create a professional, but open-source CAD Package for linux/unix systems. The system will eventually include a plugin interface as well as scripting capability, possibly through pearl, bash or other language. Development
Status: Planning
Licancia: GPL

-> gnu-cad-cam http://gnu-cad-cam.sourceforge.net/ will be a gnu gpled integrated cad/cam package. It will support hexapod machines, and conventional cnc machines.
Licancia: GPL

-> GtkCAD http://sourceforge.net/projects/gtkcad/ aims at developing a modular, full featured, modern CAD/CAE/CAM system for GNU/Linux. It will take advantage of parallel processing as appropiate. It will depend on the free software libraries GTK+,and Mesa3D.
Status: In stage of planning
Licancia: GPL

-> IDOL http://balder.prohosting.com/~projidol/ is a project to create a 3D CAD software for GNU/Linux based on OpenGL and QT. Very early stage of development.
Licancia: GPL

-> JCad http://javacad.sourceforge.net/ is a smart 2D CAD application written completely in Java. It uses the AutoCAD DXF, which is the most widely-used 2D CAD format, as its native format.
Licancia: GPL

-> LeoCAD http://leocad.gerf.org/ a CAD application that uses plastic building bricks similar to those found in many toys. This is the Linux port of the original MS Windows version, it uses OpenGL for the graphics and allows the creation of very large/complex models with a library of over 1300 different parts.
Licancia: GPL

-> lignumCAD http://sourceforge.net/projects/lignumcad/ will be a parametric solid modeling tool oriented towards the design of furniture.Development Status: Planning
Licencia: GPL

-> oCADis http://www.nocrew.org/software/ocadis/ is a 2D CAD system for Linux. It has all the basic drawing objects implemented: line, arc, circle and more. It supports HPGL (export), DXF (import and export), PostScript output.
Licencia: GPL

-> PowerCAD http://PowerCAD.sourceforge.net/ a project to develop a fully functional 3D-CAD application for Linux/BSD.
Status: In planning.
Licencia: GPL

-> PythonCAD http://www.pythoncad.org/ PythonCAD is a CAD package written in Python. The PythonCAD project aims to produce a scriptable, open-source, easy to use CAD package for Linux.
Licencia: GPL

-> QCad http://www.ribbonsoft.com/qcad.html a very powerful and easy to use CAD program for Linux. It uses DXF as its standard file format and it offers support for HPGL. While other CAD packages get complicated to use and unclear, QCad stays comfortable and even an absolute begginner can create professional drawings with a minimum of effort.
Licencia: GPL

-> QS Cad http://sourceforge.net/projects/qscad/ Pure Tcl/Tk EDA Package. Schematic capture through to PCB layout. Has Part editor as well as editor for Schematic and PCB Decals.
Status: Beta
Licencia: GPL

-> SagCAD http://sagcad.sourceforge.jp/ SagCAD aims to be an easy to use 2D CAD/CAM System with .dxf import/export, Ellipse, Polyline, SPLINE, BSPLINE, possibility to glue external programs via shell commands, CAM module (generation of ISO NC-Data), import of NC files etc.
Status: Beta
Licencia: GPL

-> Sailcut CAD http://sailcut.sourceforge.net/ is a sail design and plotting software. It allows you to design and visualise your own sail and compute the accurate development of all panels in flat sheets.
Licencia: GPL

-> ThanCAD http://thancad.sourceforge.net/ is a 2dimensional cad, with raster inclusion capability and emphasis in engineering. It is being written in Python and since it uses the wxPython library, it will hopefully be platform independent! It will also be easy to translate it to various languages. ThanCad is still in very early state.
Licencia: GPL

-> VARKON http://www.tech.oru.se/cad/varkon/ a completely open general purpose interactive modeling system but also a programming language, an object oriented database, a sculptured surface modeler, fully parametric in 2D and 3D. It can even be used as a 2D drafting system when this is needed. It is not intended for the average end user but rather for those who wish to develop CAD related functionality of their own.
Licencia: GPL

-> xSpace http://xspace.sourceforge.net/ CAD Software in a very early
stage of development. Sourcforge.net project page:
http://sourceforge.net/projects/xspace/
Licencia: GPL