FreeCAD - An open-source parametric 3D modeler
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.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
Onshape - Onshape is the first full-cloud 3D CAD system. It runs in a web browser and on any mobile device.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.