CYPECAD - Reliable structures, very precise drawings
FreeCAD - An open-source parametric 3D modeler
Robot Structural Analysis Professional - Structural Analysis and Design
OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
STAAD.Pro - Structural Analysis and Design.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.