Blender - Blender is the open source, cross platform suite of tools for 3D creation.
3D Model Maker - Model creating software designed for tablets.
Wings 3D - Wings 3D is a subdivision modeler inspired by Nendo and Mirai from Izware.
SketchUp - 3D for Everyone
Sketchfab - Sketchfab is an industrial design software tool is useful for ideation and for beginners in the industrial design field.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.