Invision - Prototyping and collaboration for design teams
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Proto.io - Create fully-interactive high-fidelity prototypes in minutes that look and work exactly like your app should. Sign up for a free 15-day trial and get started.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.