Paint with natural brushes with individual configuration, and even custom brushes, using Artweaver
Artweaver is a free program that simulates natural brush tools.
Its workplace in general resembles PhotoShop. It doesn’t open fast, although it’s not that slow as Photoshop.
Features: Individual palettes can be displayed or hidden. Simple selection of pre-defined brushes. Each brush possesses different settings, which can be changed to own needs. Individual adjustment of the brushes for specific purposes, and more.
Custom brushes can be added too, which is a nice option.