The millimeter-thick paperboard behaves just like plastic; it's strong, transparent, shapeable—and can hold boiling water.

We tried coffee tumblers from the biggest brands to finally settle the Stanley vs. YETI debate. Here's what we learned.

The square canister is the true star of the show, though, and its shape is great for optimizing storage. It's not clear if the canister is airtight (or food-safe), so to be extra cautious, I'd only ...