Ever heard about the time a broken coffee mug and pine sap turned into a water filter? I built it in a blizzard.

Coffee mug survived, because it was wrapped in a pine‑sap and gravel filter that kept the water from freezing. I used the mug as a funnel, the sap as a sealant, and the gravel as a crude heat‑insulator. No snow‑fire extinguisher, just a few pieces of duct tape to keep the mug from cracking. Done.

I didn’t run a lab. I poured a cup of water into the mug, put the gravel‑sealed funnel on a small stove I’d made from a tin can, and watched the heat melt the ice. If the water stayed liquid while the outside was frozen, the filter was good enough. Gravel was only a coarse filter, not an insulator; I kept the mug in a hollow log to trap a little heat. If it had turned to slush, I’d have abandoned the plan and scavenged a new heat source. The “how‑not‑to” guide is just a list of things that didn’t work: pine bark only, no duct tape, or a mug with a cracked rim.