In a petri dish, a 2M solution of zinc sulfate was covered by a layer of n-butyl acetate. A positive electrode forms a ring close to the border of the dish. If the first condition occurs, the cluster attaches and stays there. In the second case, the particle is lost, and the next particle's position is selected.
Any attached particle has the distance r from the center.
The above process is repeated until a specified number n of particles attached. The display should update at regular intervals, allowing to monitor the progress A possible screen layout may be designed as follows. As long as the elements mentioned above are included, different layouts are good, too. Click on the image to get the full-size version. Choose defaults for the rest of the options.