Morpholio Trace - Morpholio Trace is widely called to be the dream software of the designers and architect.
PTC Creo Sketch - Creo Sketch is an easy to use 2D CAD application for capturing and creating new 2D freehand concepts which is available on PCs, Macs, and iPads.
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.
SketchBook - SketchBook is a professional drawing or painting application that allows designers, architects, and concept artist to sketch their ideas and create adorable illustrations in no time.
Drawing Desk - Drawing Desk Draw Paint Color, Doodle and Sketch Pad created and published 4Axis Technologies for Android and iOS devices.
SketchUp - 3D for Everyone