Parametric 2d/3d CAD

 SolveSpace is a parametric 2d/3d CAD program. Applications include:
 .
  * modeling 3d parts — draw with extrudes, revolves, helix creation,
    and Boolean (union / difference / intersection) operations;
  * modeling 2d parts — draw the part as a single section, and export DXF,
    PDF, SVG; use 3d assembly to verify fit;
  * 3d-printed parts — export the STL or other triangle mesh expected by
    most 3d printers;
  * preparing CAM data — export 2d vector art for a waterjet machine or
    laser cutter; or generate STEP or STL, for import into third-party
    CAM software for machining;
  * mechanism design — use the constraint solver to simulate planar or
    spatial linkages, with pin, ball, or slide joints;
  * plane and solid geometry — replace hand-solved trigonometry and
    spreadsheets with a live dimensioned drawing.