This started as an attempt to draw Sol LeWitt’s Wall Drawing 16:

Bands of lines 12 inches (30 cm) wide, in three directions (vertical, horizontal, diagonal right) intersecting.

As you can see, I didn’t do a great job of following the instructions. I never even made it all the way to the third band of lines. I got sidetracked trying to implement that nice animated pencil drawing effect.

See the code for details but in a nutshell it works by breaking each line down into lots of tiny segments. Each segment is drawn with a randomized width on every frame, which gives it that wiggly appearance.