Designer and animator Guy walks through his process on creating procedural metal materials using Octane Renderer in Cinema4D. He shows how you can dial in various metal types as well as how to add imperfections to help generate more realistic results. Since these materials are procedural, meaning they use algorithms instead of bitmap textures, they are highly flexible and extendable.
I followed this tutorial months ago when I was exploring how to create a library of metal materials. The IOR site he references is invaluable and one I have bookmarked. The video is short and dense, which is great if you're familiar with Octane, but can be daunting if you're just getting started. The section on procedural imperfections flies by, but the more you become comfortable with Octane's Node Editor the easier it is to see what he's doing. A lot of what he's doing is repetitive. Nodes such as UV Transform, Gradient, Dirt and Noise will become your friends the more you dive into Octane or any renderer for that matter. He sells his package of metal materials at a great price. I recommend picking them up for your own projects or even to be able to open each material up in the Node Editor so you can spend more time understanding how they are constructed.
Spacergif dropped this excellent tutorial on modeling a 3D character in Cinema4D. This style of 3D character is fairly popular these days and knowing there are countless ways to build 3D objects I was intrigued by his method of using C4D's Volume Builder and Mesher. The video is less than 40mins in length, so easy to watch during your lunch break, and I highly recommend checking it out.
If you're not familiar with Volumes then here's a short overview of how they work. Volumes allow you to build 3D objects quickly and in a non-destructive manner. Essentially you dump objects (primitives or editable meshes) inside a Volume Builder, arranging and editing them however you want to build up a base for your object. You can even do boolean operations on these objects (add A to B, subtract B from A, etc) which is super powerful. The Volume Builder all the while is representing this grouping of objects as a single object comprised of voxels. C4D then generates a single mesh when you place the Builder inside of a Mesher. The Mesher and Builder both give you options to dial-in the overall fidelity of your final mesh.
One of my favorite 3D studios gave me a little insight into their process by sharing they use the Volume Builder in C4D to produce their incredible work. Figuring out how to efficiently utilize these tools is still something I'm exploring but the potential is there.