KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
SolidWorks - Dassault Systèmes SolidWorks Corp. develops and markets 3D CAD design software, analysis software, and product data management software. SolidWorks is the leading supplier of 3D CAD product design engineering software.
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
FreeCAD - An open-source parametric 3D modeler
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
SketchUp - 3D for Everyone