>>95830118
I was living in Asia back then and some of the fancy hipster coffee shops give disposable corrugated plastic cover with their cups, so you don't get burned with the hot coffee. I hoarded them to use in terrains.
I have never seen these outside of Asia, however greenstuff world has this, to make corrugated metal: https://www.greenstuffworld.com/en/texturing-tools/357-corrugator-tool-for-corrugated-metals.html
You can also find corrugated cardboard in art or paper shops.