I was just playing around with custom blocks - I hardly ever use them. Each randomly sized dot will spawn at a random place - in the beginning, they'll spawn towards the middle, then they'll slowly work outwards. The dots will all scout around their spawning area, and if they find no other dots, they'll settle down and stop moving. If they find another dot, either settled or moving, they'll disappear.
I had some inspiration to use custom blocks when I saw the showcase for projects that used many customs on the front page. Heeeey, I'm in the studio! Nice, and thanks!