SketchBook Express is free!
Sketchbook Express is available from the Mac App Store for free. It’s designed to act as an entrylevel introduction to AutoDesk’s SketchBook Pro, but is a very capable painting application in its own right.
It has a good selection of brushes, pens, and other tools, and has support for multiple layers. You can add text to your images too, and import bitmap images to trace them. It also includes full support for Wacom’s tablets, and an option to allow you to control stylus sensitivity. Initially launched as an iPad app, its touch-screen origins are apparent in its user interface, which takes a little getting used to. There are limitations; you can’t save or export with layers intact, for example, and there’s no option to change the texture of the media onto which you draw or paint. Some may, ahem, bristle at the lack of custom options for brushes when compared to Painter, but if what you want is a tool to make quick sketches or to practice your drawing, SketchBook Express is bang on the money.