PVC comes in multi-inch diameters (with big prices), mailing tubes might come in a workable size. Oatmeal and some supplements come in large cardboard cylindrical containers.
You can improve their appearance with a paper or styrene wrapper, paint, and weathering.
I'd use the pvc pipe, as I did for silos on my HO scale layout.
For O gauge, you might find the Classic Toy Trains group a big help.
Hover your mouse over Community, and go to the forums.
Mike.
My You Tube
I’m planning an O scale switching layout a la David Barrow’s MRP 2018 article about returning to O.
Coming from an agricultural part of the world, my thoughts are how to build O scale silos. Can I use Walthers HO silos and ignore what differences in scale there are? Slice up PVC pipe with the more correct width and live with the difference.
Or ask the forum group for their constructive ideas.
I await your helpful suggestion.
Murray