There has been a lot of interest in Arnold for Cinema 4D. Pingo van der Brinkloev had some great resources on Arnold for cinema 4D on the last Cinema 4d Advanced Production Techniques (C4DAPT2).
Here, Pingo shows how to deal with OpenVDB Volumes in Arnold for Cinema 4D. It is a crash course on creating OpenVDB volumes using Houdini and rendering with Arnold for C4D.
Pingo previously posted a look into using the highly anticipated Arnold for C4D showing how easy it is to get production quality renders quickly.
C4DAPT2 is an on-demand title that will cover everything from physical based rendering techniques with V-Ray, Octane Render and Arnold.
The presentations are jam-packed with tips and tricks for optimization, in depth shading techniques and studies from actual productions.