Press the flag to randomly generate a crystal similar to that of bismuth. Turbo Mode (press the flag while holding shift) generates it instantly, if you don't care to see the actual process.
I really wanted to create something to generate something similar to bismuth crystals in Scratch, and this is the result. It's not perfect, but it's good enough for now. Since hexagons are the bestagons, I hexagon-ised it - go to https://scratch.mit.edu/projects/1008851751/