Thank you for the file, David.
Please have a look at the file below.
CV4_2024_drs_24_TXgr_01.c4d
Screenshot 2024-05-01 at 11.31.00 AM.jpg
Here, I have added a second cylinder with the "Thicken" object, as it matters whether the object is based on "volume" or "wall" geometry.
I do not see any mistakes in your material setup, as I need more input on what you wanted to achieve.
Without that information, pretty much any critic would be from my point of view only, perhaps missing what you would like to have. Criticizing without knowing one's intention is not what I like to do here.
It would be my idea of things, and I can share it, but it is more important that you get what you want and know how to get there.
A good idea is always to search for reference material. I would avoid web-based stuff and shoot your own. Why? Because you do not know how the image was treated, such as through color correction, etc. With that, it is more of a reference to the artist who has created it. If that difference can be spotted and reverse-engineered, you get faster to your idea about it (if it is a fitting reference or not).
If you explore material settings, keep the render size small, as fast feedback (shorter render times) is critical to adjusting things quickly.
Leave perhaps GI (and AO) entirely out for the first rounds of setting up the material.
I hope that helps more than telling you a few parameter settings. Anyway, let me know what you want, and we can discuss how to get you there.
Cheers