Film still colour study painted on the touchscreen of my Nintendo 3DS using an eShop app called Colors! 3D.
Colors! operates in an interesting way - it records your work as a series of brushstrokes, so it can "re-paint" the image at different resolutions without any loss of quality. (Substance Painter does something similar I think.)
These means you can create playback videos where your artwork magically paints itself. Have a look!
Timelapse video