FreeCAD - An open-source parametric 3D modeler
Morpholio Trace - Morpholio Trace is widely called to be the dream software of the designers and architect.
SketchUp Make - SketchUp Make is a best in the class CAD software capable of performing 2D and 3D rendering and designing, however, best for the 2D projects.
DWG FastView - DWG FastView for Windows is a lightweight dwg/dxf drawing viewer and editor produced by Gstarsoft, no need of dwg format conversion, vector graph magnified without distortion and full compatible with AutoCAD DWG/DXF.
QCAD - QCAD is an application for computer aided drafting in 2D.
Drawing Desk - Drawing Desk Draw Paint Color, Doodle and Sketch Pad created and published 4Axis Technologies for Android and iOS devices.