Messing around with the Android "Kids Paint" app this morning. I deny any and all artistic ability, and the resemblance to any real-life machines is purely unintentional and coincidental. Richard Polt has nothing to fear!
My wife originally found this app and installed it on her phone a while back as a kid-entertainer for my youngest. As you can probably tell, it randomly changes the color of your "pen" for each stroke, which gives the artwork a very pop-art sensibility. This hopefully compensates for lack of perspective, realism or (in the case of the upstrike) screen space.