Old wooden barrel can be used as pet house to accommodate your dog or cat in garden. Barrel would nicely blend in the garden. However you need some support work for the barrel to stay where you put it and not to roll away
Rocket stove in use - everyone needs to know how to build/use one of these for "those" times when there's no other way to cook. (My Junior Girl Scout Handbook showed this stove made with a large coffee can.