Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
SketchUp - 3D for Everyone
MediBang Paint - The official site for MediBang Paint, the free digital painting and manga creation software. You can download the latest version of MediBang Paint here, and get news and tutorials.
AC3D - AC3D is a 3D software for games, virtual reality and flight simulation, scientific, medical and general data visualisation, rapid prototypes of 3D designs, 3D printing, Google Earth, X-Plane, Second Life and more.
Corel Painter - Corel Painter is media painting software.