Slide the "length" slider to change the length of the password. Feel free to take the custom blocks; one generates a list from a string, one generates a random string from a list, and the other shuffles a list.
I am not a cyber security professional, but this is pretty good for a Scratch project. This starts off with a basic list of available letters and symbols. The list is then shuffled using the Durstenfeld Shuffle. A password is then picked from random spots in the list to a fitting length. To-do: - shuffle the final password - add option for human-readable passwords