Bodypaint 3D is an image editing application that unites all the necessary 3D tools in one window: colors, materials, layers, animations and structure. Principally used to create animations for video games or cartoons it gives you some liberty in the creation process by letting you see the results of your work in real time.
Since the main screen shows your work directly in 3D instead of 2D, you can get a good idea of colors and shapes, and using the mouse to zoom in or out is really easy. The only drawback would be that Bodypaint tends to use a high level of your CPU, around 72 MB when we tested it. The program also has extended render settings offering the likes of batch rendering, render active objects or rendering a region.