@SinisterLefty Fireproof lock box on granite slab is perfect!
For the small 1S LiPo, I use a metal tray that is large enough to hold both charger and LiPos. Another thing I’ve seen people use is a glass or ceramic baking pan.
Two other things to consider: (1) Keep any combustibles at a distance, e.g. charge in your garage, or at least kitchen or (dry) bathroom. (2) I also recommend getting a small (spray can size) fire extinguisher from the hardware store. I picked up a bunch of First Alert Tundra fire extinguisher sprays at Home Depot ($25 for 2x on Amazon). They are not certified for places where a fire extinguisher is required by law. However, they work extremely well for fires small and large. I have several around the house, and one in my car as well.
For storage of charged LiPos (100 percent or storage charge), I use LiPo bags for smaller packs and metal ammunition boxes for larger packs. I either leave them ajar or remove the seal in order to prevent pressure buildup in case of fire.