Solvespace is a free parametric 2D/3D CAD tool including:

* 3D modeling with extrudes, revolves and boolean operations
* 2D modeling as a single section and export to DXF, PDF and SVG
* 3D printing features, as a STL export expected by 3D printers
* CAM data preparing, exporting 2D vector art for waterjet machine or
  laser cutter, or generating STEP or STL
* Mechanism design with a constraint solver to simulate planar or
  spatial linkages with pin, ball or slide joints
* Plane and solid geometry, replacing hand-solved trigonometry and
  spreadsheets with a live dimensioned drawing
