TextureLab - Free, Cross-Platform, GPU-Accelerated Procedural Texture Generator.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
NeoTextureEdit - NeoTextureEdit is an open source (GNU LGPL v.
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.
GraphicDesignerToolbox - Graphics editor for composing textures, buttons, logos, icons.
ZBrush - ZBrush is a digital sculpting and painting software solution.