Cross-platform Open-source 2D CAD
DXF2GCODE: converting 2D dxf drawings to CNC machine compatible G-Code
Draw vector graphics to scale using a descriptive language
Another drawing editor for LaTeX with PSTricks & TikZ
SOLVESPACE is a free (GPLv3) parametric 3d CAD tool.
Application for management of CAD files and projects
Insert PDF into DWG in AutoCad. Autolisp Frontend for PSTOEDIT