Ignore post #3 and watch the video. Its (almost) unbelievable.
And to think, 54 years ago worm paintings were the rage.
Place canvas flat face up.
Put a small bowl of worms mixed with pigment in the center.
Allow the worms to crawl out and to the edge of the canvas.
When done, lift off bowl, and with a small round brush fill in the empty connections to the worm trails.