I’ve make quite a few of these paper towel holders at this point. They are pretty straightforward. You can use brackets or screws from the back to secure the sides. The backing is wood so you can pre-drill and locate the paper towel holder where you want it. The sides can be any material really.

The steel pipe used to secure the roll is the most important part.

If you use a wooden dowel in the same method, the lesser weight tends to let the dowel slide back and forth. The steel pipe rod is heavy enough to stay still. There is a clear coat on the steel pipe to keep if from rusting when it gets damp.