SolveSpace is a free (GPLv3) parametric 2d/3d CAD (computer-aided design) tool. Applications include:

• Modeling 3d parts — draw with extrudes, revolves/helix, and Boolean operations
• Modeling 2d parts — draw the part as a single section, and export; use 3d assembly to verify fit
• Modeling 3d-printed parts — export the STL or other triangle mesh expected by most slicers
• Preparing 2D CAM data — export 2d vector art for a waterjet machine or laser cutter
• Mechanism design — use the constraint solver to simulate planar or spatial linkages
• Plane and solid geometry — replace hand-solved trigonometry with a live dimensioned drawing