Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Boxy SVG - Boxy SVG is a vector graphic editor built for the modern web.
Sculptris - Sculptris: Enter a world of digital art without barriers.
ShapeShop - ShapeShop is an advanced and professional 3D design and modeling application that comes with an easy-to-use and user-friendly interface.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Misfit Model 3D - Misfit Model 3D is a 3D model editor that basically operates with triangle-based models.