Photoshop is a wonderful software suite to use for digital art creation. It does have plenty of bells and whistles to give you lots of control. With BrushKnob, you will have an external controller for Photoshop. It controls the brush size and has a switch to go from the brush to eraser tools.
To get started, simply connect the device to your computer, and you are ready to go. Your computer will recognize the device as an external keyboard. BrushKnob is portable and has an open-source design. More information is available on Indiegogo.