This is a quick, abstract rendering I did, using Arnold for Cinema 4D, to try a technique from this Grayscale Gorilla tutorial. The tutorial uses Cinema4d materials to achieve an effect of one color in the middle and blending to another color on the exterior. I have not figured out how to achieve this effect using Arnold but I will keep experimenting. Arnold is fairly new to me and I am still learning it.
Abstract Renderings
I first came across abstract renderings like these on RonenBekerman.com. Since then I have seen a bunch of people recreating these types of renders. I thought I would give it a try. I found this tutorial which showed the technique in Cinema4D. The images below are my attempt at this kind of abstract render.