I am a lazy artist. For example, for a recent piece, I wanted a curvy set of train tracks, like this:

But I wanted to be able to see what the whole curve would look like without having to paintstakingly draw each of the little tracks.

So, I wrote a little application which would let me draw a stroke on my iPad, and automatically draw a set of train tracks along it.

The application adds a bit of randomness to the strokes and the spacing, and has sliders for controlling a bunch of parameters of how the tracks are rendered along the drawn path.