In the end, I forewent using Toxi’s library and instead opted to implement particle systems because I wanted a better understanding of how to use them. Here is a video of the end result. I added some perlin noise to vary the color and add a bit more sparkle to the “crystals.” But the code is using four particle systems which hit the “seeds,” each of which are generated upon a mouse press. As the particles hit the seeds, they will become part of the seed and expand the cluster, forming the branching-like DLA pattern.

source code here