LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
SketchUp - 3D for Everyone
FreeCAD - An open-source parametric 3D modeler
Autodesk AutoCAD - Autodesk AutoCAD is a commercial computer-aided design (CAD) and drafting software application.
nanoCAD - nanoCAD is a pro-grade 2D CAD system with native DWG support and full customizability.
OpenBuilds CAM & Control - OpenBuilds CAM & Control are two major applications that enable users to connect, manipulate, and convert drawings for use with DragKnife, CNC, Plasma, or Laser devices.