Free CAD software
Draftsight by Dassault Systemes
Draftsight is excellent 2D CAD drawing program made by Dassault Systemes who also make the renowned SolidWorks 3D
Windows and MAC beta are available.
With DraftSight it's possible for you to send dwg or dxf files for us to machine from.
Google SketchUp have a free version that is good for creating 3D concept models and is very popular with architects and designers.
Unless you upgrade to the professional version we are unable to machine from Google SketchUp files.